How to pass information between activities using rating bar

How to pass information between activities using rating bar - java

Ok, so im pretty new to android and the whole app making but im just doing like a generic app rating thing just for practice. Here are the details I have just 2 generic pictures on the main activity with a rate button beside each and a text view below them both so when you click the rate button it takes you to the second activity which has the rating bar. This is my problem in the view with the rating bar I just have the display for the rating as a toast but i want to be able to take that rating and display it inside the textview in my main activity and its posing more of a problem than i thought it was going to so im looking for a bit of help
this is the code for my main activity
package com.example.brent.appmanagement;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ratingapp1();
ratingapp2();
getrating();
}
private void getrating(){
}
private void ratingapp1(){
Button rateapp1 = findViewById(R.id.rateapp1);
rateapp1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startActivity(new Intent(MainActivity.this, firstapp.class));
}
});
}
private void ratingapp2(){
Button rateapp2 = findViewById(R.id.rateapp2);
rateapp2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startActivity(new Intent(MainActivity.this, secondapp.class));
}
});
}
}
and this is the code for the activity with the rating bar
public class firstapp extends AppCompatActivity {
public RatingBar ratingBar;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_firstapp);
ratingBar = findViewById(R.id.ratingBar);
return1();
}
public void rateMe(View view){
Toast.makeText(getApplicationContext(),
String.valueOf(ratingBar.getRating()),
Toast.LENGTH_LONG).show();
}
private void return1(){
Button returntomain1 = findViewById(R.id.returntomain1);
returntomain1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startActivity(new Intent(firstapp.this, MainActivity.class));
}
});
}
}
also I have the XML which i dont know if you need to see but here it is
main activity
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.brent.appmanagement.MainActivity">
<Button
android:id="#+id/rateapp1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="96dp"
android:layout_marginTop="124dp"
android:text="Rate"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/rateapp2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="176dp"
android:layout_marginEnd="96dp"
android:text="Rate"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent" />
<ImageView
android:id="#+id/imageView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="96dp"
android:layout_marginTop="112dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#mipmap/ic_launcher" />
<ImageView
android:id="#+id/imageView4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="164dp"
android:layout_marginStart="96dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:srcCompat="#mipmap/ic_launcher" />
<TextView
android:id="#+id/savedrating1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="96dp"
android:layout_marginTop="12dp"
android:text=""
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/imageView3" />
<TextView
android:id="#+id/savedrating2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="96dp"
android:layout_marginTop="12dp"
android:text=""
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/imageView4" />
</android.support.constraint.ConstraintLayout>
and the second activity
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.brent.appmanagement.firstapp">
<Button
android:id="#+id/returntomain1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginStart="8dp"
android:text="Return to main menu"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<TextView
android:id="#+id/rate_me"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:text="Rate Me"
android:textSize="18dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<RatingBar
android:id="#+id/ratingBar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/rate_me"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:numStars="5"
android:stepSize="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/rate_me" />
<Button
android:id="#+id/submit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/ratingBar"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:onClick="rateMe"
android:text="Submit"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/ratingBar" />
</android.support.constraint.ConstraintLayout>
I would like to have the rating from the rating bar inside firstactivity be displayed in the textview savedrating1 inside my main activity
thanks all in advance for the help

for primitive values you can stuff them inside the intent using key value pairsIntent intent =new Intent(); String myValue="something";intent.putExtra("keyMyValue",myValue);startActivity(intent); for passing custom objects use parcelable and stuff the parcelable into the intent as above or here

Related

setOnClickListener crashes the app - Android

I've 3 activity in my app. I set setOnClickListener on all the imagebutton in all the 3 activity. When I run the application and on clicking the first button in the first activity the app crash, but if I comment out addListenerOnButton code in the second activity the app works just fine. Any help is appreciated
This is the code of MainActivity.java
package com.example.caa;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.ImageButton;
import android.view.View;
public class MainActivity extends AppCompatActivity {
ImageButton maschio, femmina;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addListenerOnButton();
}
public void addListenerOnButton() {
maschio = (ImageButton) findViewById(R.id.Uomo);
femmina = (ImageButton) findViewById(R.id.Donna);
maschio.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
Intent i = new Intent(MainActivity.this, Scelta_Simbolo.class);
String genere = "maschio";
i.putExtra("genere", genere);
startActivity(i);
/*SERVE PER VEDERE DIRETTAMENTE SU SCHERMO UN MESSAGGIO
Toast.makeText(MainActivity.this,
"ImageButton is clicked!", Toast.LENGTH_SHORT).show();*/
}
});
femmina.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
Intent i = new Intent(MainActivity.this, Scelta_Simbolo.class);
String genere = "femmina";
i.putExtra("genere", genere);
startActivity(i);
}
});
}
}
And activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#drawable/sfondo"
tools:context=".MainActivity">
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Pagina 1 - TEST"
android:textAlignment="center"
android:textColor="#FFFFFF"
android:textSize="24sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.497"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.057" />
<ImageButton
android:id="#+id/Donna"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#00FFFFFF"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.826"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.661"
app:srcCompat="#drawable/woman" />
<ImageButton
android:id="#+id/Uomo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#00FFFFFF"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.793"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.238"
app:srcCompat="#drawable/man" />
<TextView
android:id="#+id/Voce_Uomo"
android:layout_width="157dp"
android:layout_height="35dp"
android:text="Voce Maschile "
android:textAlignment="center"
android:textColor="#FFFFFF"
android:textSize="24sp"
android:textStyle="bold|italic"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.208"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.28" />
<TextView
android:id="#+id/Voce_Donna"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Voce Femminile"
android:textAlignment="center"
android:textColor="#FFFFFF"
android:textSize="24sp"
android:textStyle="bold|italic"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.218"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.629" />
</androidx.constraintlayout.widget.ConstraintLayout>
This is second class code: Scelta_Simbolo.java (without comment on setOnClickListener so in this case crash)
package com.example.caa;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageButton;
public class Scelta_Simbolo extends MainActivity {
ImageButton si_no, su_giu, ok_nope;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scelta_simbolo);
addListenerOnButton();
}
public void addListenerOnButton() {
si_no = (ImageButton) findViewById(R.id.si_no_button);
// su_giu = (ImageButton) findViewById(R.id.su_giu_button);
// ok_nope = (ImageButton) findViewById(R.id.ok_nope_button);
Bundle receiveBundle = this.getIntent().getExtras();
final String receiveValue = receiveBundle.getString("genere");
si_no.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
/* Intent i = new Intent(Scelta_Simbolo.this, Ripr_Audio.class);
String scelta = "si_no";
i.putExtra("scelta", receiveValue);
startActivity(i);*/
}
});
/* su_giu.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
Intent i = new Intent(Scelta_Simbolo.this, Ripr_Audio.class);
String scelta = "su_giu";
i.putExtra("scelta", scelta);
startActivity(i);
}
});
ok_nope.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
Intent i = new Intent(Scelta_Simbolo.this, Ripr_Audio.class);
String scelta = "ok_nope";
i.putExtra("scelta", scelta);
startActivity(i);
}
});
*/
}
}
And the xml activity_scelta_simbolo.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#drawable/sfondo">
<TextView
android:id="#+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Pagina 2 - TEST"
android:textAlignment="center"
android:textColor="#FFFFFF"
android:textSize="24sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.497"
app:layout_constraintStart_toStartOf="#+id/textView3"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.057" />
<TextView
android:id="#+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Scegli quale tipologia di simboli vuoi utlizzare:"
android:textAlignment="center"
android:textColor="#FFFFFF"
android:textSize="25sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.149" />
<ImageButton
android:id="#+id/si_no_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#00FFFFFF"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="#+id/textView2"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="#+id/textView2"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.336"
app:srcCompat="#drawable/si_no" />
<ImageButton
android:id="#+id/su_giu_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#00FFFFFF"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="#+id/si_no_button"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="#+id/si_no_button"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.531"
app:srcCompat="#drawable/su_giu" />
<ImageButton
android:id="#+id/ok_nope_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#00FFFFFF"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="#+id/su_giu_button"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="#+id/su_giu_button"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.728"
app:srcCompat="#drawable/ok_nope" />
</androidx.constraintlayout.widget.ConstraintLayout>
Thank you

How to set a textView to visible after an onClick event and Activity change?

I have three passages in my scrollview that need to each become visible after an onclick event on one of three buttons.
I have currently set them to all invisible. And since I cannot get it to work, I am only trying it out with one of the passages.
Because of this I created a private textview constant for only the first passage. But after I pass the intent to switch the activity, I also try to turn the view on that package to visible.
I have included my MainActivity.java and the xml file I used to set invisible.
package com.example.threebuttons;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
private TextView passage1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
passage1 = findViewById(R.id.passage_1);
}
public void launchPassageOne(View view) {
passage1.setVisibility(view.VISIBLE);
Intent intent = new Intent(this, PassageActivity.class);
startActivity(intent) ;
}
public void launchPassageTwo(View view) {
Intent intent = new Intent(this, PassageActivity.class);
startActivity(intent) ;
}
public void launchPassageThree(View view) {
Intent intent = new Intent(this, PassageActivity.class);
startActivity(intent) ;
}
}
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".PassageActivity">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<EditText
android:id="#+id/passage_1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:gravity="start|top"
android:inputType="textMultiLine"
android:text="#string/passage1"
android:visibility="invisible"/>
<EditText
android:id="#+id/passage_2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:gravity="start|top"
android:inputType="textMultiLine"
android:text="#string/passage2"
android:visibility="invisible"/>
<EditText
android:id="#+id/passage_3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:gravity="start|top"
android:inputType="textMultiLine"
android:text="#string/passage3"
android:visibility="invisible"/>
</LinearLayout>
</ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>
My program just crashes. And I cannot find any error messages.
How can I make the packages visible whenever I want the activity to change?
There are three passages that I want to each become visible for the respective button, then turn invisible if the back button is pressed.

It seams the three views are in the started activity. And so you can't change their visibility because they haven't been created.
Add this before you start the activity
intent.putExtra("passageNum", 1)
Then call startActivity(intent)
In PassageAactivity onCreate do the following :
If (getIntent().hasExtra("passageNum") && getIntent().getExtras().getInt("passageNum") == 1)
passage1.setVisibility(View.VISIBLE)
And so on for the other views

passage1.setVisibility(View.VISIBLE)
read more about views and how to modify their behavior here :
https://developer.android.com/reference/android/view/View

Use View.VISIBLE, capital V, it's a integer constant from the View class. Remove the View argument from the method launchPassageOne:
public void launchPassageOne() {
passage1.setVisibility(View.VISIBLE);
Intent intent = new Intent(this, PassageActivity.class);
startActivity(intent) ;
}

Image click hereWhatever I understood with your code I got that you are not initializing your methods in On create, whatever defined outside the On create will not be used until or unless called from inside On create method.
Designed some code may help you understanding in a better way.
In below code, I made text views scrollable, but you can only scroll if text is too long to fill the entire textview.
MainActivity.java
package com.example.threebuttons;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.text.method.ScrollingMovementMethod;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
EditText edit1;
EditText edit2;
EditText edit3;
Button btn1;
Button btn2;
Button btn3;
Button btnV;
Button btnI;
TextView t1;
TextView t2;
TextView t3;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// defining id for edit texts
edit1=findViewById(R.id.passage_1);
edit2=findViewById(R.id.passage_2);
edit3=findViewById(R.id.passage_3);
// defining id for buttons
btn1=findViewById(R.id.button_1);
btn2=findViewById(R.id.button_2);
btn3=findViewById(R.id.button_3);
btnV=findViewById(R.id.btnvisi);
btnI=findViewById(R.id.btninvisi);
// defining id for text views
t1=findViewById(R.id.textview1);
t2=findViewById(R.id.textview2);
t3=findViewById(R.id.textview3);
// making text views scrollable
t1.setMovementMethod(new ScrollingMovementMethod());
t2.setMovementMethod(new ScrollingMovementMethod());
t3.setMovementMethod(new ScrollingMovementMethod());
btn1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
t1.setText(edit1.getText().toString());
}
});
btn2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
t2.setText(edit2.getText().toString());
}
});
btn3.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
t3.setText(edit3.getText().toString());
}
});
btnV.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//Making passages Visible
t1.setVisibility(View.VISIBLE);
t2.setVisibility(View.VISIBLE);
t3.setVisibility(View.VISIBLE);
}
});
btnI.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
t1.setVisibility(View.INVISIBLE);
t2.setVisibility(View.INVISIBLE);
t3.setVisibility(View.INVISIBLE);
}
});
}
}
Set activitymain.xml as below
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#2196F3"
tools:context=".MainActivity">
<EditText
android:id="#+id/passage_1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
android:ems="10"
android:hint="passage 1"
android:inputType="textPersonName"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.043"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.016" />
<EditText
android:id="#+id/passage_2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
android:ems="10"
android:hint="Passage 2"
android:inputType="textPersonName"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.043"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.102" />
<EditText
android:id="#+id/passage_3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
android:ems="10"
android:hint="Passage 3"
android:inputType="textPersonName"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.043"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.194" />
<Button
android:id="#+id/button_1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
android:text="Button"
app:layout_constraintBottom_toTopOf="#+id/passage_2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/passage_1"
app:layout_constraintTop_toTopOf="#+id/passage_1" />
<Button
android:id="#+id/button_2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
android:text="Button"
app:layout_constraintBottom_toTopOf="#+id/passage_3"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/passage_2"
app:layout_constraintTop_toTopOf="#+id/passage_2" />
<Button
android:id="#+id/button_3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:text="Button"
app:layout_constraintBottom_toBottomOf="#+id/passage_3"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/passage_3"
app:layout_constraintTop_toTopOf="#+id/passage_3" />
<TextView
android:id="#+id/textview1"
android:layout_width="319dp"
android:layout_height="74dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
android:background="#3F51B5"
android:hint="Passage 1"
android:scrollbars="vertical"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.486"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.446"
tools:visibility="invisible" />
<TextView
android:id="#+id/textview2"
android:layout_width="319dp"
android:layout_height="74dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
android:background="#3F51B5"
android:hint="Passage 2"
android:scrollbars="vertical"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.672"
tools:visibility="invisible" />
<TextView
android:id="#+id/textview3"
android:layout_width="319dp"
android:layout_height="74dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
android:background="#3F51B5"
android:hint="Passage 3"
android:scrollbars="vertical"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.486"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.895"
tools:visibility="invisible" />
<Button
android:id="#+id/btnvisi"
android:layout_width="175dp"
android:layout_height="44dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
android:text="Passage Visible"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.036"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.299" />
<Button
android:id="#+id/btninvisi"
android:layout_width="174dp"
android:layout_height="47dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
android:text="passage invisible"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.886"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.3" />
</androidx.constraintlayout.widget.ConstraintLayout>
I hope it makes you understand in a better way,
Thanks

How do I reference to layout objects (XML) using Java to develop apps?

This is for example my XML code:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="26dp"
android:text="Wat wil je gemiddeld komen te staan?"
android:textAlignment="center"
android:textSize="30sp"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="#+id/editText1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:hint="Typ het hier in"
android:inputType="numberDecimal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView" />
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:gravity="center"
android:text="Volgende"
android:background="#ff0000"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/editText1" />
This is my Java code so far:
package com.firstapp.myapplication;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public static void main(String[] args) {
}
}
Lets say I want EditText to have a maximum input of 2 decimals, how do I reference to in Java to make these changes? So I basically want to add the logic to the XML layout objects but I don't know how to address them in Java.

public class MainActivity extends AppCompatActivity {
private EditText editText1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText1=findViewById(R.id.editText1);
Editable decimalNumber=editText1.getText();
}
}
XML Layout changes for limiting input(maxLength)
<EditText
android:id="#+id/editText1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:maxLength="2"
android:gravity="center"
android:hint="Typ het hier in"
android:inputType="numberDecimal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView" />

Firstly, there won't be any main method in android
Please start writing your code in onCreate method after
setContentView(R.layout.activity_main);

How to keep the values of first activity and see them on switching back from second activity to first activity

I entered some text in the text boxes on first activity.
Then, On pressing the "SAVE" button, I am moved to the second activity.
Now, On pressing the "BACK" button, I am dropped back on the first activity where i am unable to see the values/text i entered before.
I have tried using shared preferences also.
Here is my code
MainActivity.java
package com.example.madhur.intentclear;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final EditText tv1 = findViewById(R.id.editText);
final EditText tv2 = findViewById(R.id.editText2);
final EditText tv3 = findViewById(R.id.editText3);
final Button bt1 = findViewById(R.id.button);
bt1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
SharedPreferences sharedPreferences1=getSharedPreferences("value1",Context.MODE_PRIVATE);
SharedPreferences.Editor editor=sharedPreferences1.edit();
editor.putString("tv1",tv1.getText().toString());
SharedPreferences sharedPreferences2=getSharedPreferences("value2",Context.MODE_PRIVATE);
SharedPreferences.Editor editor2=sharedPreferences2.edit();
editor2.putString("tv2",tv2.getText().toString());
SharedPreferences sharedPreferences3=getSharedPreferences("value3",Context.MODE_PRIVATE);
SharedPreferences.Editor editor3=sharedPreferences3.edit();
editor3.putString("tv3",tv3.getText().toString());
editor.apply();
editor2.apply();
editor3.apply();
tv1.setText(String.valueOf(sharedPreferences1.getString("tv1",null)));
tv2.setText(String.valueOf(sharedPreferences2.getString("tv2",null)));
tv3.setText(String.valueOf(sharedPreferences3.getString("tv3",null)));
Intent intent = new Intent(MainActivity.this, Main2Activity.class);
intent.putExtra("tv1",tv1.getText().toString());
intent.putExtra("tv2",tv2.getText().toString());
intent.putExtra("tv3",tv3.getText().toString());
startActivity(intent);
}
});
}
}
Main2Activity.java
package com.example.madhur.intentclear;
import android.content.Context;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.io.FileOutputStream;
import java.io.IOException;
public class Main2Activity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
final TextView tv1=findViewById(R.id.textView);
final TextView tv2=findViewById(R.id.textView2);
final TextView tv3=findViewById(R.id.textView3);
Button button=findViewById(R.id.button);
Button button1=findViewById(R.id.button1);
Button button2=findViewById(R.id.button2);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Bundle intent=getIntent().getExtras();
tv1.setText(intent.getString("tv1"));
tv2.setText(intent.getString("tv2"));
tv3.setText(intent.getString("tv3"));
}
});
button1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String clear="";
tv1.setText(clear);
tv2.setText(clear);
tv3.setText(clear);
m1();
}
});
button2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent1=new Intent(Main2Activity.this,MainActivity.class);
startActivity(intent1);
}
});
}
public void m1()
{String clear="";
try {
FileOutputStream fileOutputStream;
FileOutputStream fileOutputStream2;
FileOutputStream fileOutputStream3;
fileOutputStream = openFileOutput("et1.txt", Context.MODE_PRIVATE);
fileOutputStream.write(clear.getBytes());
fileOutputStream2 = openFileOutput("et2.txt", Context.MODE_PRIVATE);
fileOutputStream2.write(clear.getBytes());
fileOutputStream3 = openFileOutput("et3.txt", Context.MODE_PRIVATE);
fileOutputStream3.write(clear.getBytes());
} catch (IOException e) {
e.printStackTrace();
}
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.madhur.intentclear.MainActivity">
<android.support.constraint.Guideline
android:id="#+id/guideline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.13" />
<android.support.constraint.Guideline
android:id="#+id/guideline2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.87" />
<android.support.constraint.Guideline
android:id="#+id/guideline3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.06" />
<android.support.constraint.Guideline
android:id="#+id/guideline4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.18" />
<android.support.constraint.Guideline
android:id="#+id/guideline5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.29" />
<android.support.constraint.Guideline
android:id="#+id/guideline6"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.43" />
<android.support.constraint.Guideline
android:id="#+id/guideline7"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.58" />
<android.support.constraint.Guideline
android:id="#+id/guideline8"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.73" />
<android.support.constraint.Guideline
android:id="#+id/guideline9"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.82" />
<android.support.constraint.Guideline
android:id="#+id/guideline10"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.95" />
<android.support.constraint.Guideline
android:id="#+id/guideline11"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.24" />
<android.support.constraint.Guideline
android:id="#+id/guideline12"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.77" />
<EditText
android:id="#+id/editText"
android:layout_width="0dp"
android:layout_height="0dp"
android:ems="10"
android:inputType="textPersonName"
android:hint="Enter name"
app:layout_constraintBottom_toTopOf="#+id/guideline4"
app:layout_constraintEnd_toStartOf="#+id/guideline2"
app:layout_constraintStart_toStartOf="#+id/guideline"
app:layout_constraintTop_toTopOf="#+id/guideline3" />
<EditText
android:id="#+id/editText2"
android:layout_width="0dp"
android:hint="Enter phone number"
android:layout_height="0dp"
android:ems="10"
android:inputType="textPersonName"
app:layout_constraintBottom_toTopOf="#+id/guideline6"
app:layout_constraintEnd_toStartOf="#+id/guideline2"
app:layout_constraintStart_toStartOf="#+id/guideline"
app:layout_constraintTop_toTopOf="#+id/guideline5" />
<EditText
android:id="#+id/editText3"
android:layout_width="0dp"
android:hint="Enter Email Adress"
android:layout_height="0dp"
android:ems="10"
android:inputType="textPersonName"
app:layout_constraintBottom_toTopOf="#+id/guideline8"
app:layout_constraintEnd_toStartOf="#+id/guideline2"
app:layout_constraintStart_toStartOf="#+id/guideline"
app:layout_constraintTop_toTopOf="#+id/guideline7" />
<Button
android:id="#+id/button"
android:layout_width="0dp"
android:layout_height="0dp"
android:text="SAVE"
app:layout_constraintBottom_toTopOf="#+id/guideline10"
app:layout_constraintEnd_toStartOf="#+id/guideline12"
app:layout_constraintStart_toStartOf="#+id/guideline11"
app:layout_constraintTop_toTopOf="#+id/guideline9" />
</android.support.constraint.ConstraintLayout>
activity_Main2.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.madhur.intentclear.Main2Activity">
<TextView
android:id="#+id/textView"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/guideline16"
app:layout_constraintEnd_toStartOf="#+id/guideline13"
app:layout_constraintStart_toStartOf="#+id/guideline14"
app:layout_constraintTop_toTopOf="#+id/guideline15" />
<TextView
android:id="#+id/textView2"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/guideline19"
app:layout_constraintEnd_toStartOf="#+id/guideline13"
app:layout_constraintStart_toStartOf="#+id/guideline14"
app:layout_constraintTop_toTopOf="#+id/guideline20" />
<TextView
android:id="#+id/textView3"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/guideline17"
app:layout_constraintEnd_toStartOf="#+id/guideline13"
app:layout_constraintStart_toStartOf="#+id/guideline14"
app:layout_constraintTop_toTopOf="#+id/guideline18" />
<android.support.constraint.Guideline
android:id="#+id/guideline13"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_begin="249dp" />
<android.support.constraint.Guideline
android:id="#+id/guideline14"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.33854166" />
<android.support.constraint.Guideline
android:id="#+id/guideline15"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.031311154" />
<android.support.constraint.Guideline
android:id="#+id/guideline16"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.13" />
<android.support.constraint.Guideline
android:id="#+id/guideline17"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.38" />
<android.support.constraint.Guideline
android:id="#+id/guideline18"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.29" />
<android.support.constraint.Guideline
android:id="#+id/guideline19"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.26" />
<android.support.constraint.Guideline
android:id="#+id/guideline20"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.16" />
<Button
android:id="#+id/button"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="52dp"
android:text="SHOW TEXT"
app:layout_constraintEnd_toStartOf="#+id/guideline13"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="#+id/guideline14"
app:layout_constraintTop_toTopOf="#+id/guideline17" />
<Button
android:id="#+id/button1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="44dp"
android:text="CLEAR TEXT"
app:layout_constraintEnd_toStartOf="#+id/guideline13"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="#+id/guideline14"
app:layout_constraintTop_toBottomOf="#+id/button" />
<Button
android:id="#+id/button2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="48dp"
android:text="BACK"
app:layout_constraintEnd_toStartOf="#+id/guideline13"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="#+id/guideline14"
app:layout_constraintTop_toBottomOf="#+id/button1" />
</android.support.constraint.ConstraintLayout>

Use savedInstanceState Bundle in onCreate
The savedInstanceState is a reference to a Bundle object that is passed into the onCreate method of every Android Activity. Activities have the ability, under special circumstances, to restore themselves to a previous state using the data stored in this bundle. If there is no available instance data, the savedInstanceState will be null.
For example, the savedInstanceState will always be null the first time
an Activity is started, but may be non-null if an Activity is
destroyed during rotation.
When do I save things to the Bundle?
All activities have an onSaveInstanceState method that can be overridden. When this method is called, any state-related data should be placed into the outState Bundle. This method is called when an Activity is being backgrounded (either after onPause() or onStop(), depending on different factors).
What should be saved?
The savedInstanceState Bundle should only save information directly related to the current Activity state. Examples of this include:
A typical example is User-submitted data – If a user writes their username into a text box, they would expect the username to still be present when the Activity is resumed. This data should be saved in onSaveInstanceState then restored when the Activity is re-created.
In your onCreate function, this Bundle is handed back to the program. The best way to check if the application is being reloaded, or started for the first time is:
if (savedInstanceState != null) {
// Then the application is being reloaded
}
To get the data back out, use the get* functions just like the put* functions. The data is stored as a name-value pair. This is like a hashmap. You provide a key and the value, then when you want the value back, you give the key and the function gets the value. Here's a short example.
#Override
public void onSaveInstanceState(Bundle outState) {
outState.putString("message", "This is my message to be reloaded");
super.onSaveInstanceState(outState);
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (savedInstanceState != null) {
String message = savedInstanceState.getString("message");
Toast.makeText(this, message, Toast.LENGTH_LONG).show();
}
}
// Promoting Local variable to Field
public class Main2Activity extends AppCompatActivity {
private TextView tv1;
private TextView tv2;
private TextView tv3;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
tv1 = (TextView) findViewById(R.id.textView);
tv2 = (TextView) findViewById(R.id.textView2);
tv3 = (TextView) findViewById(R.id.textView3);
...
}
}

Use shared Preference to store values temporally/ permanent
EDITED
Sorry i was not seen the code after seen code.
Your setting values inside onlCick again. You have set the values outside the onClick
Solution
Create one global SharedPreferences with MODE_PRIVATE, set the values onClick and read values on onCreate(outside onClick).

How to make ImageButton clickable in Android Studio?

I have done an immense amount of research and for whatever reason whatever I try I cannot get an ImageButton to be clickable in Android studio. I have tried numerous things but I must be missing something. I will past XML file below and then Java below that. When I put setOnClickListener method I get a cannot resolve message and same for when I do onClickListener. I would like the button to link to a webpage. Please help!
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.autismacademyed.www.autismacademy.AutismAcademy">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAlignment="center"
android:textColor="#android:color/black"
android:textSize="36sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.173" />
<ImageView
android:id="#+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="#drawable/logo"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintHorizontal_bias="0.0" />
<ImageButton
android:id="#+id/imageButtonYellow"
android:layout_width="109dp"
android:layout_height="125dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:background="#null"
android:scaleType="centerCrop"
android:visibility="visible"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toBottomOf="#+id/imageView2"
app:srcCompat="#mipmap/ic_yellowpuzzlepiece"
android:onClick="onClick"/>
</android.support.constraint.ConstraintLayout>
Here is Java:
package com.autismacademyed.www.autismacademy;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ImageButton;
public class AutismAcademy extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_autism_academy);
}
ImageButton imageButtonYellow = (ImageButton)findViewById(R.id.imageButtonYellow);
imageButtonYellow.setOnClickListener(new View.onClickListener()
public void onClick (View v) {
Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://www.aaed.org"));
startActivity(browserIntent);
}
}

Remove the setOnClickListener since you already specify in your view that the onclick function for the button is onClick. To avoid confusion rename your button android:onClick="onClick", like android:onClick="imageButtonOnClick".
And in your java code you can just use this
package com.autismacademyed.www.autismacademy;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ImageButton;
public class AutismAcademy extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_autism_academy);
}
public void imageButtonOnClick(View v) {
Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://www.aaed.org"));
startActivity(browserIntent);
}
}

Just copy and paste this two file will work for you. You declare two click listener that's why its not working.
xml file
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.autismacademyed.www.autismacademy.AutismAcademy">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAlignment="center"
android:textColor="#android:color/black"
android:textSize="36sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.173" />
<ImageView
android:id="#+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="#drawable/logo"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintHorizontal_bias="0.0" />
<ImageButton
android:id="#+id/imageButtonYellow"
android:layout_width="109dp"
android:layout_height="125dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:background="#null"
android:scaleType="centerCrop"
android:visibility="visible"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toBottomOf="#+id/imageView2"
app:srcCompat="#mipmap/ic_yellowpuzzlepiece"
android:onClick="buttonClick"/>
</android.support.constraint.ConstraintLayout>
jAVAFILE
public class AutismAcademy extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_autism_academy);
}
public void buttonClick(View v) {
Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://www.aaed.org"));
startActivity(browserIntent);
}
}

Develop Reference

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

How to pass information between activities using rating bar - java

for primitive values you can stuff them inside the intent using key value pairsIntent intent =new Intent(); String myValue="something";intent.putExtra("keyMyValue",myValue);startActivity(intent); for passing custom objects use parcelable and stuff the parcelable into the intent as above or here

Related

setOnClickListener crashes the app - Android

How to set a textView to visible after an onClick event and Activity change?

How do I reference to layout objects (XML) using Java to develop apps?

How to keep the values of first activity and see them on switching back from second activity to first activity

How to make ImageButton clickable in Android Studio?

Categories

Resources