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Android Floating Action Button not being recognized

When I look at my code in the editor, nothing seems to be a problem. However, when I run the code on my phone and try to go from one activity to another which features a floating action button, the floating action button cannot find the view by Id despite the ID being exactly the same in both java and XML.
My Java:
package com.test.app.app2_test1;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
public class TermsOfUse extends AppCompatActivity {
FloatingActionButton mFloatingActionButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.terms_of_use);
mFloatingActionButton = (FloatingActionButton) mFloatingActionButton.findViewById(R.id.terms_back_fab);
mFloatingActionButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
onBackPressed();
}
});
}
}
My XML:
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
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.test.app.app2_test1.TermsOfUse"
android:background="#color/backdrop">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="44dp"
android:orientation="vertical">
</ScrollView>
<View
android:layout_gravity="bottom"
android:layout_width="match_parent"
android:layout_height="44dp"
android:background="#color/colorPrimary"
android:elevation="4dp"/>
<android.support.design.widget.FloatingActionButton
android:id="#+id/terms_back_fab"
android:layout_gravity="bottom"
android:layout_width="56dp"
android:layout_height="56dp"
android:layout_margin="16dp"
android:src="#drawable/ic_arrow_back"
app:pressedTranslationZ="12dp"/>
</android.support.design.widget.CoordinatorLayout>
The message that I get in my console is the following:
Attempt to invoke virtual method 'android.view.View android.support.design.widget.FloatingActionButton.findViewById(int)' on a null object reference
Any help would be appreciated.

You are treating a view as a child of its own!
Replace:
mFloatingActionButton = (FloatingActionButton) mFloatingActionButton.findViewById(R.id.terms_back_fab);
With:
mFloatingActionButton = (FloatingActionButton)findViewById(R.id.terms_back_fab);

Android error:R cannot be resolved to a variable

Actually i read the answers but i am in a confused state of what to do now.I am using Eclipse and i get the errors in the lines--
setContentView(R.layout.activity_main);
Clickhere=(Button)findViewById(R.id.button1);
getMenuInflater().inflate(R.menu.main,menu);
Here is the following code:-
package com.example.vaish;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
public class MainActivity extends Activity {
Button Clickhere;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Clickhere=(Button)findViewById(R.id.button1);
Clickhere.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent i=new Intent(getApplicationContext(),MainActivity1.class);
startActivity(i);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main,menu);
return true;
}
}
XML file:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#drawable/happy"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="" />
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:text="Clickhere" />
</RelativeLayout>
please help!!!
i need to get the errors cleared off.

Try cleaning your project, If R.java is still not build, there can be errors in your project. You can check exact errors in Problems tab as shown in below image:
Resolve the errors, then clean and build your project.

#Vaishnavi this is not an Error.
Means it is the Error in your XML file...Check XML File First.
Otherwise Try to Clean Your Project OR Build Your Project Properly.
That will solved Your Problem.
Don't Forget (R.) error will never Solve untill you will Remove Your Error from XML File.
Hope this will help you...(:

if setContentView(R.layout.activity_main); is line of code which cause of application crash it means you have written incorrect tags or syntax error.
What is your XML Layout code?

``
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="" />
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:text="Clickhere" />
``

Add this import statement
import <your.package.name>.R;
For instance
import com.shivam.cleaner.R;

Error on creating button listener first android app

As this is my first android app; i couldn't figure out what goes wrong.
Error
Error on line "caller.textView.setText(“You clicked the button!”);"
Multiple markers at this line
Syntax error, insert "AssignmentOperator Expression" to complete
Assignment
Syntax error, insert ";" to complete BlockStatements
Line breakpoint:MyOnClickListener [line: 12] - onClick(View)
setText cannot be resolved or is not a field
screenshot of error
MainActivity.java
package com.example.myfirstandroidapp;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity {
Button button;
TextView textView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new MyOnClickListener(this));
textView = (TextView) findViewById(R.id.textView1);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
MyOnClickListener.java
package com.example.myfirstandroidapp;
import android.view.View;
import android.view.View.OnClickListener;
public class MyOnClickListener implements OnClickListener {
MainActivity caller;
public MyOnClickListener(MainActivity activity) {
this.caller = activity;
}
public void onClick(View view) {
caller.textView.setText(“You clicked the button!”);
}
}
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello_world" />
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/textView1"
android:layout_below="#+id/textView1"
android:layout_marginTop="70dp"
android:text="Button" />
</RelativeLayout>

Can anyone explain me how the execution process runs in this java code for Fragments in Android Studio [closed]

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Closed 7 years ago.
Improve this question
I wrote this code according to the video tutorial found here
about Android Fragments, but I can't understand how the flow of execution runs through these codes. As in the tutorial I have made two fragments alone with the Main Activity. The whole program works fine, but I can't understand how the execution flow goes. Please be kind enough to explain me. Here are my source codes, I am
really sorry as they are too long, I posted all of my code. This is the Main Activity.java
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends ActionBarActivity implements top_layout_fragment.TopSelectionListener {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
//overiding the method from the interface
#Override
public void createMeme(String top, String bottom) {
bottom_layout_fragment bottomLayoutFragment = (bottom_layout_fragment) getSupportFragmentManager().findFragmentById(R.id.fragment2);
bottomLayoutFragment.setText(top, bottom);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
this is the activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin" tools:context=".MainActivity">
<fragment
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:name="com.example.kasun.fragments.top_layout_fragment"
android:id="#+id/fragment"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
tools:layout="#layout/top_layout_fragment" />
<fragment
android:layout_width="320dp"
android:layout_height="320dp"
android:name="com.example.kasun.fragments.bottom_layout_fragment"
android:id="#+id/fragment2"
tools:layout="#layout/bottum_layout_fragment"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true" />
</RelativeLayout>
this is the top_layout_fragment.java
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.View;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.Button;
import android.app.Activity;
import java.util.ServiceConfigurationError;
public class top_layout_fragment extends Fragment {
private static EditText firstText, secondText;
TopSelectionListener activityCommand;
public interface TopSelectionListener {
public void createMeme(String top, String bottom);
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
activityCommand = (TopSelectionListener) activity;
}
catch(ClassCastException e){
throw new ClassCastException (activity.toString());
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.top_layout_fragment, container, false);
firstText = (EditText) view.findViewById(R.id.firstText);
secondText = (EditText) view.findViewById(R.id.secondText);
final Button button = (Button) view.findViewById(R.id.button);
button.setOnClickListener(
new View.OnClickListener() {
public void onClick(View v) {
buttonClicked(v);
}
}
);
return view;
}
public void buttonClicked(View view) {
activityCommand.createMeme(firstText.getText().toString(), secondText.getText().toString());
}
}
this is top_layout_fragment.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent">
<EditText
android:id="#+id/firstText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:width="320dp"
android:layout_marginTop="20dp"
android:layout_centerHorizontal="true"
/>
<EditText
android:id="#+id/secondText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:width="320dp"
android:layout_marginTop="20dp"
android:layout_centerHorizontal="true"
android:layout_below="#id/firstText"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_below="#+id/secondText"
android:layout_marginTop="20dp"
android:text="#string/button_Texg"
android:id="#+id/button" />
</RelativeLayout>
this is the bottom_layout_fragment.java
package com.example.kasun.fragments;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.View;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import android.widget.TextView;
public class bottom_layout_fragment extends Fragment {
private TextView topText,bottomText;
// need to overide the onCreateViewMethod
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.bottum_layout_fragment,container,false);
topText=(TextView)view.findViewById(R.id.topText);
bottomText=(TextView)view.findViewById(R.id.bottomText);
return view;
}
public void setText(String topText,String bottomText){
this.topText.setText(topText);
this.bottomText.setText(bottomText);
}
}
this is the bottom_layout_fragment.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent"
android:background="#drawable/image1">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Large Text"
android:id="#+id/topText"
android:layout_marginTop="34dp"
android:textColor="#FFF"
android:gravity="center_horizontal"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Large Text"
android:id="#+id/bottomText"
android:layout_alignParentBottom="true"
android:layout_alignLeft="#+id/topText"
android:layout_alignStart="#+id/topText"
android:layout_marginBottom="35dp"
android:textColor="#FFF"
android:gravity="center_horizontal" />
</RelativeLayout>

This is set up so you have one activity displaying two fragments. You can see both fragments are included in the activities layout file.
The top fragment needs to communicate with the bottom one to update its text and does so through an interface called TopSelectionListener. You will notice that your activity implements that interface. The other important part is the top fragment keeps a reference to your activity using the interface. You can see that in the top fragment's onAttach method. The activity displaying this fragment must implement the TopSelectionListener interface or else you will get a ClassCastException and your application will crash.
activityCommand = (TopSelectionListener) activity;
When the button is clicked in the top fragment it will call activityCommand.createMeme(...) which calls the createMeme method in your activity.
The createMeme method then looks up a reference to your bottom Fragment and calls the setText method on it to update the text it shows.
There is another example how this works in the Android documentation.

Eclipse, Creating Android Projects, won't import javax.swing

I normally create android apps using either eclipse or NetBeans but when I try to create a messagebox on button press, Eclipse in this case won't import javax.swing
activity_main.xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="136dp"
android:text="Button" />
</RelativeLayout>
MainActivity.java:
package com.example.understanding;
import android.os.Bundle;
import android.app.Activity;
import javax.swing;
import android.view.Menu;
import android.view.View;
public class MainActivity extends Activity {
private void button1_ButtonActionPerformed(View v) {
JOptionPane.showMessageDialog(null, "Enter Account Details");
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}

javax.swing does not exist on Android and is not part of the Android SDK.