unfortunately app has stopped error when Changing the graphical layout

Question

I'm new to android development. I created a simple app that adds two numbers Using eclipse. It worked fine. But when I run the app after changing the positions of buttons and textViews, using graphical layout without directly editing xml files, "unfortunately app has stopped" error shown in Emulator. This happens to me few times. Please can someone figure why is that?

logCat

06-10 16:51:36.690: E/Trace(1343): error opening trace file: No such file or directory (2)
06-10 16:51:36.886: D/AndroidRuntime(1343): Shutting down VM
06-10 16:51:36.886: W/dalvikvm(1343): threadid=1: thread exiting with uncaught exception (group=0xa624b288)
06-10 16:51:36.890: E/AndroidRuntime(1343): FATAL EXCEPTION: main
06-10 16:51:36.890: E/AndroidRuntime(1343): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.a/com.example.a.MainActivity}: java.lang.ClassCastException: android.widget.RadioGroup cannot be cast to android.widget.Button
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.ActivityThread.access$600(ActivityThread.java:130)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.os.Handler.dispatchMessage(Handler.java:99)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.os.Looper.loop(Looper.java:137)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.ActivityThread.main(ActivityThread.java:4745)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at java.lang.reflect.Method.invokeNative(Native Method)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at java.lang.reflect.Method.invoke(Method.java:511)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at dalvik.system.NativeStart.main(Native Method)
06-10 16:51:36.890: E/AndroidRuntime(1343): Caused by: java.lang.ClassCastException: android.widget.RadioGroup cannot be cast to android.widget.Button
06-10 16:51:36.890: E/AndroidRuntime(1343):     at com.example.a.MainActivity$PlaceholderFragment.onCreateView(MainActivity.java:75)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1500)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:570)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1163)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.Activity.performStart(Activity.java:5018)
06-10 16:51:36.890: E/AndroidRuntime(1343):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2032)
06-10 16:51:36.890: E/AndroidRuntime(1343):     ... 11 more

fagment_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:gravity="fill"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:background="#EB7474"
tools:context="com.example.a.MainActivity$PlaceholderFragment" >

<EditText
    android:id="@+id/n1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:layout_marginLeft="23dp"
    android:layout_marginTop="119dp"
    android:ems="10"
    android:background="#FFE9E9"
    android:hint="num2" >

    <requestFocus />
</EditText>

<EditText
    android:id="@+id/n2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/n1"
    android:layout_alignBottom="@+id/n1"
    android:layout_alignParentRight="true"
    android:layout_marginRight="20dp"
    android:ems="10"
    android:background="#FFE9E9"
    android:hint="num2" />

<Button
    android:id="@+id/b1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/radioGroup1"
    android:layout_marginTop="99dp"
    android:layout_toRightOf="@+id/n1"
    android:text="Answer" />

<TextView
    android:id="@+id/tv1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/b1"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="69dp"
    android:background="#FFE9E9"
    android:text="@string/hello_world" />

<RadioGroup
    android:id="@+id/radioGroup1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/n1"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="132dp"
    android:orientation="horizontal" >

    <RadioButton
        android:id="@+id/r0"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checked="true"
        android:text="+" />

    <RadioButton
        android:id="@+id/r1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="-" />

    <RadioButton
        android:id="@+id/r2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="X" />

    <RadioButton
        android:id="@+id/r3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="/" />
</RadioGroup>

</RelativeLayout>

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.a.MainActivity"
tools:ignore="MergeRootFrame" />

mainActivity.java

package com.example.a;

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
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.EditText;
import android.widget.RadioGroup;
import android.widget.TextView;
import android.os.Build;

public class MainActivity extends ActionBarActivity {

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

    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 {


    Button A;
    TextView B;
    EditText n1;
    EditText n2;
    RadioGroup radioButtonGroup;

    public PlaceholderFragment() {
    }

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



        A = (Button) rootView.findViewById(R.id.b1);
        B = (TextView) rootView.findViewById(R.id.tv1);
        n1 = (EditText) rootView.findViewById(R.id.n1);
        n2 = (EditText) rootView.findViewById(R.id.n2);
        radioButtonGroup = (RadioGroup) rootView.findViewById(R.id.radioGroup1);

        A.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub


                int radioButtonID = radioButtonGroup.getCheckedRadioButtonId();
                View radioButton = radioButtonGroup.findViewById(radioButtonID);
                int idx = radioButtonGroup.indexOfChild(radioButton);

                int num1 = Integer.parseInt(n1.getText().toString());
                int num2 = Integer.parseInt(n2.getText().toString());
                int total = 0;
                switch (idx)
                {
                case 0:
                    total = num1+num2;
                    break;

                case 1:
                    total = num1-num2;
                    break;

                case 2:
                    total = num1*num2;
                    break;

                case 3:
                    total = num1/num2;
                    break;

                case -1:
                    break;
                }

                String ttl = String.valueOf(total);
                B.setText(ttl);

            }
        });



        return rootView;
    }
}

}

Answer 1

I usually get this error when all I am doing is swapping view in xml layout. It is a ecllipse bug(sometimes) when and as a result your resource is not synced with the adt builder. When I get his error first thing I do is close ecllipse, end process adb.exe from task manager(windows) and then start ecllipse again. If this doesnot help then Android tools -> fix project properties and project -> clean.

Answer 2

android.widget.RadioGroup cannot be cast to android.widget.Button

• Your XML contains a RadioGroup item

• Your Fragment class is getting that item with findViewById and tries to cast it as a Button. Like that for instance:

  Button btn = (Button) getView().findViewById(r.id.myRadioButton);

You'll need to either change your XML to make that a element or to change your fragment to get a RadioGroup variable:

RadioGroup grp = (RadioGroup) getView().findViewById(r.id.myRadioButton);

Answer 3

The problem is that you are trying to cast a RadioGroup to a Button, which you can't do. This is happening in MainActivity.

Post the code for MainActivity if you can't find the problem.

Answer 4

As I suspected, I don't see any invalid casting going on. My guess is that you're receiving this error because there is some disconnect between what has been deployed and what you've got built in your IDE. R.java is probably stale. You need to clean (remove bin, gen, lib, obj directories) and rebuild your project.

Here's a similar post where this same thing happened: Android ClassCastException for RadioGroup into RadioButton

Their issue was resolved by shutting down the emulator and restarting the IDE.

Answer 5

this is simple one! I had came across this once. It seems quite baffling & frustrating at first, but the only thing you need to do is help eclipse get aware of the fact that the position and layout of a few (or all) components have been modified/altered. And this you are supposed to achieve by building the work space from scratch. For that all you need to do is close and restart eclipse. That'll do.