What's wrong with Eclipse (Unfortunately app has stopped) [closed]

StackOverflow https://stackoverflow.com/questions/23661200

  •  22-07-2023
  •  | 
  •  

Question

I'm pretty new with eclipse im trying to set the text with the help of a button on eclipse (just first steps in learning)

But whenever i identify an onSetClickListener and try to run application on emulator i get this error "Unfortunately app has stopped"

Here are my codes

MainActivity.java

package com.example.androidjii;

import android.support.v7.app.ActionBarActivity;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends ActionBarActivity {

Button changer;
TextView changeme;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

changer = (Button) findViewById(R.id.change1);
changeme = (TextView) findViewById (R.id.changeme1);
changer.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
changeme.setText("Changed");
}
});
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
}


@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;
}

@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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}

/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {

public PlaceholderFragment() {
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}

}

fragment_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal"
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="com.example.androidjii.MainActivity$PlaceholderFragment" >

<TextView
    android:id="@+id/changeme1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:gravity="center"
    android:text="@string/yazi" />

<Button
    android:id="@+id/change1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_below="@+id/changeme1"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="29dp"
    android:text="Change It" />

</RelativeLayout>

Need your help to solve it. What is wrong with my codes or way?

Update: activity_main.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.androidjii.MainActivity"
tools:ignore="MergeRootFrame" />
Was it helpful?

Solution

This is because findViewById() searches in the activity_main layout, while the button is located in the fragment's layout fragment_main.

Move that piece of code in the onCreateView() method of the fragment:

//...

View rootView = inflater.inflate(R.layout.fragment_main, container, false);
Button buttonClick = (Button)rootView.findViewById(R.id.button);
buttonClick.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        onButtonClick((Button) view);
    }
});

Notice that now you access it through rootView view:

Button buttonClick = (Button)rootView.findViewById(R.id.button);

otherwise you would get again NullPointerException.

In your code, move

changer = (Button) findViewById(R.id.change1);
changeme = (TextView) findViewById (R.id.changeme1);
changer.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
changeme.setText("Changed");
}
});

to onCreateView() method of the fragment

Licensed under: CC-BY-SA with attribution
Not affiliated with StackOverflow
scroll top