Develop Reference

TextView wont redirect me to my registration activity from login

When I click on the Sign up txt on my application it crashes I've tried almost everything i could find including the XML onClick
XML clickable
onClick
public class LoginActivity extends AppCompatActivity
{
TextView sign_up_text;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
sign_up_text = (TextView) findViewById(R.id.sign_up);
sign_up_text.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(LoginActivity.this, RegisterActivity.class));
}
});
}
}
xml:
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/sign_up_text"
android:textSize="18dp"
android:gravity="center"
android:layout_alignParentBottom="true"
android:id="#+id/sign_up"
android:clickable="true"
android:onClick="onClick"
/>
Android app crashes with no failure

You have android:onClick="onClick" attribute in your xml. And you have also define sign_up_text.setOnClickListener in java.
You can do only one thing at a time.
1.
If you want to use sign_up_text.setOnClickListener , you simply need to remove android:onClick="onClick" from xml file.(Reference)
2.
If you want to use android:onClick="onClick", you should define new method in your activity like:(Reference)
public void onClick(View view) {
}

First solution is to remove android:onClick="onClick" from your XML, according to my perception the reason of crash is the function name called on onClick of your button click define in XML is "onClick" which is also override function of setOnClickListner
#Override
public void onClick(View v){
//todo your code
}
Second Solution is if you use onClick in XMl change function name other that override function onClick like:
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/sign_up_text"
android:textSize="18dp"
android:gravity="center"
android:layout_alignParentBottom="true"
android:id="#+id/sign_up"
android:clickable="true"
android:onClick="myFunction"
/>
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
}
private myFunction(View view){
}

Android Java Occur a method event

Hello I want that my methods work instantly when the user enters the application.
For now I have an onClick event in my xml which activates so to say my methods(this works).
the xml:
<TextView
android:id="#+id/cd_start"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fontFamily="sans-serif-light"
android:gravity="center"
android:paddingBottom="0dp"
android:text="time"
android:textColor="#000"
android:textSize="21sp"
android:onClick="dateEnd"/>
and Main Activity.java
String dateStopKukuk = "21 Dec 2015";
private void displayDateEnd(String etime) {
TextView priceTextView = (TextView) findViewById(R.id.cd_start);
priceTextView.setText(etime);
}
public void dateEnd(View v) {
displayDateEnd(dateStopKukuk);
}

Edit: I added a comments to explain you this code.
Try this:
import android.app.Activity;
import android.view.View;
import android.widget.TextView;
public class MainActivity extends Activity implements View.OnClickListener
{
// onClick method is called when one of view is clicked. (you must use setOnClickListener on this View to inform system to call this)
#Override
public void onClick(View v)
{
// check if clicked view is cd_start
if(v.getId() == R.id.cd_start)
{
// true cd_start is clicked
displayDateEnd(dateStopKukuk);
}
}
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState); // REQUIRED!!! When you don't add this your app will be crash.
setContentView(R.layout.activity_main); // sets activity_main as layout (if you use different name of layout replace activity_name with your layout name)
findViewById(R.id.cd_start).setOnClickListener(this); // finds view with cd_start id and sets click listener. When this view is clicked system calls onClick method.
// and now your code what do you want to do when activity is creating.
}
String dateStopKukuk = "21 Dec 2015";
private void displayDateEnd(String etime) {
TextView priceTextView = (TextView) findViewById(R.id.cd_start);
priceTextView.setText(etime);
}
/* You don't need dateEnd method now */
}
XML:
<TextView
android:id="#+id/cd_start"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fontFamily="sans-serif-light"
android:gravity="center"
android:paddingBottom="0dp"
android:text="time"
android:textColor="#000"
android:textSize="21sp"
/> <!-- You don't need android:onClick -->
In your activity.
I hope it helped you.

Unknown entity Id

I created a normal button in main.XML and in Java I added added a Toast message when clicking it. My problem is I need to hide it when clicked, but that involves R.id.main or something like that. The problem is I get the error "Unknown entity 'id'". Am I missing imports?
Imports:
package com.redstonelamp.DroidRedstoneLamp;
import android.app.*;
import android.os.*;
import android.view.*;
import android.widget.*;
import android.view.View. *;
Code:
public class MainActivity extends Activity
{
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public void confirmClicked(View view){
Toast.makeText(getApplicationContext(), "Please choose a version to download",
Toast.LENGTH_LONG).show();
}
}

If you want to hide your button you have two possibilities :
1. With a Listener
Let's say you have this XML file :
main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="#+id/my_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
In your main class you will need to retrieve your Button and subscribe your MainActivity to the click event of this button.
MainActivity
public class MainActivity extends Activity implements View.onClickListener
{
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
// this will inflate all the UI elements you have added
// in your main.xml file
setContentView(R.layout.main);
// here you retrieve the button in the layout by its ID
Button myButton = findViewById(R.id.my_button);
// here you tell your button he should propagate the
// Click event to this Activity.
myButton.setOnClickListener(this);
}
#Override
public void onClick(View view)
{
// here you handle the click
// the view parameter is the view that was clicked
// therefore your button :)
// so all you have to do is to set it's visibility
view.setVisibility(View.INVISIBLE);
}
}
2. Directly by naming the method
The mechanism behind is the same but this one allows you to have a custom method name. To do this you will have to add a field in the XML file named : onClick.
This field will contain the name of the method that will handle the click.
This method has to be implemented in the Activity / Fragment in which you have inflated this Button (with the setContentView method).
main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="#+id/my_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="myOnClickMethod" />
</LinearLayout>
Then in your MainActivity :
MainActivity
public class MainActivity extends Activity implements View.onClickListener
{
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
// this will inflate all the UI elements you have added
// in your main.xml file
setContentView(R.layout.main);
}
public void myOnClickMethod(View view)
{
// here you handle the click
// the view parameter is the view that was clicked
// therefore your button :)
// so all you have to do is to set it's visibility
view.setVisibility(View.INVISIBLE);
}
}
Hope this will help you.
Cheers

Relative Layout All Childs Clickable

This Question Is Pretty Silly to ask but out, but i Would like to know how it Works?
I had a Relative Layout with 2 ImageViews as Child having separate clickListner instances. One above Another, of same Size and Attributes.
Overlaps Each other. Both having Different images.
Question is When i click on one image both ImageView Click listners are Called.
Or if i disable the Click on ImageView Top, The ImageView Below Still Works, I was Clicking on Image View Above though. How it is I'ts Getting callback from both.
I Just Want to know How it works? not The code, i do not have any issue writing code for clickListners Whether only one Working or Both.
<RelativeLayout
----
---
>
<ImageView
---
---<!--Child 1-->
<ImageView
---
---<!--Child 2-->
<RelativeLayout/>

Taken from here:
if you are working with just one clicklistener, you can do:
View.OnClickListener myOnlyhandler = new View.OnClickListener() {
public void onClick(View v) {
switch(v.getId()) {
case R.id.b1:
// it was the first button
break;
case R.id.b2:
// it was the second button
break;
}
}
}

Use ImageButton
Layout
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<ImageButton
android:id="#+id/imageButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:contentDescription="#string/content"
android:src="#drawable/ic_launcher" />
</LinearLayout>
Activity class
public class MainActivity extends Activity {
ImageButton imgButton;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
addButtonListener();
}
public void addButtonListener() {
imgButton = (ImageButton) findViewById(R.id.imageButton);
imgButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
Toast.makeText(MainActivity.this,"ImageButton is working!", Toast.LENGTH_SHORT).show();
}
});
}
}

Give this to your parent layout
android:context="Yourclasshere"
then give this to your image view
android:onclick="onclick"
and then implement the on click listener or make the method like Vitly A make above

Changing the position of the thumb of the SeekBar using a different Button

I'm trying to move the position of the seekbar using a button. Basically I have a seekbar from 0 to 100. and I have button presents set up at arbitrary values (40,50,60 etc). When I try to set the progress on the seekbar via button, I get a fault.. I've already initialized the seekBar in the onCreate() method.
SeekBar seekBar = (SeekBar) findViewById(R.id.seekBar1);
currentProgress = 40;
seekBar.setMax(100);
seekBar.setProgress(currentProgress);
button40.setOnClickListener(button40Listener);
But when use the below, it crashes.
private OnClickListener button40Listener = new OnClickListener() {
public void onClick(View v) {
currentProgress = 40;
seekBar.setProgress(currentProgress);
}
}
This seems straight-forward. Any ideas?

You shouldn't need to put up another Seekbar. The initial one should be fine. Without the exception message and stack trace I'm not sure what is causing the crash. However, I just coded an example and works as you would expect. Perhaps by looking at my example you can identify your issue.
SeekbarTest.java:
package com.example.seekbartest;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.SeekBar;
public class SeekbarTest extends Activity {
/** Called when the activity is first created. */
private SeekBar seekBar;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
seekBar = (SeekBar)findViewById(R.id.seekBar1);
Button fortyPctButton = (Button)findViewById(R.id.buttonFortyPct);
fortyPctButton.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View v)
{
seekBar.setProgress(40);
}
});
Button sixtyPctButton = (Button)findViewById(R.id.buttonSixtyPct);
sixtyPctButton.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View v)
{
seekBar.setProgress(60);
}
});
Button eightyPctButton = (Button)findViewById(R.id.buttonEightyPct);
eightyPctButton.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View v)
{
seekBar.setProgress(80);
}
});
}
}
And here is the main.xml it is referencing for the layout:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView
android:layout_width="fill_parent"
android:text="#string/hello"
android:id="#+id/textView1"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"/>
<SeekBar
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/seekBar1"
android:layout_below="#+id/textView1"
android:layout_alignLeft="#+id/textView1"
android:layout_alignRight="#+id/textView1"/>
<Button
android:layout_width="wrap_content"
android:text="40%"
android:id="#+id/buttonFortyPct"
android:layout_height="wrap_content"
android:layout_below="#+id/seekBar1"
android:layout_alignLeft="#+id/seekBar1"/>
<Button
android:layout_width="wrap_content"
android:text="60%"
android:id="#+id/buttonSixtyPct"
android:layout_height="wrap_content"
android:layout_toRightOf="#+id/buttonFortyPct"
android:layout_alignTop="#+id/buttonFortyPct"
android:layout_alignBottom="#+id/buttonFortyPct"/>
<Button
android:layout_width="wrap_content"
android:text="80%"
android:id="#+id/buttonEightyPct"
android:layout_height="wrap_content"
android:layout_toRightOf="#+id/buttonSixtyPct"
android:layout_alignTop="#+id/buttonSixtyPct"
android:layout_alignBottom="#+id/buttonSixtyPct"/>
</RelativeLayout>
Just create a new android app and replace the generated code + layout with the example above. It should work for you.
Good luck,
Craig