Question

Trying to write my first app on android.
But the app crashes(FC) on the virtual device when clicking any of buttons.
Please take a look..
the MainActivity.java:

public class MainActivity extends Activity {
public EditText t1 = null, t2 = null;
Button b1 = null, b2 = null;
TextView tv1 = null,tv2 = null;
int a = 0, b = 0, S1 = 0, S2 = 0;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    t1=(EditText)findViewById(R.id.editText1);
    t2=(EditText)findViewById(R.id.EditText2);
    b1=(Button)findViewById(R.id.button1);
    b2=(Button)findViewById(R.id.button2);
    tv1=(TextView)findViewById(R.id.TextView1);
    tv2=(TextView)findViewById(R.id.TextView2);


}
public void onClick1() 
{
    tv1.clearComposingText();
  a=Integer.parseInt(t1.getText().toString());
   tv1.setText(S1+=a);
   }

public void onClick2() 
{
    tv2.clearComposingText();
  b=Integer.parseInt(t2.getText().toString());
   tv2.setText(S2+=b);
   }

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}

}

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" >

<Button
    android:id="@+id/button1"
    android:layout_width="80dp"
    android:layout_height="60dp"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:layout_marginLeft="30dp"
    android:layout_marginTop="30dp"
    android:text="Add"
    android:onClick="onClick1" />

<Button
    android:id="@+id/button2"
    android:layout_width="80dp"
    android:layout_height="60dp"
    android:layout_alignBaseline="@+id/button1"
    android:layout_alignBottom="@+id/button1"
    android:layout_marginLeft="26dp"
    android:layout_toRightOf="@+id/button1"
    android:text="Add"
    android:onClick="onClick2" />

<EditText
    android:id="@+id/editText1"
    android:layout_width="80dp"
    android:layout_height="60dp"
    android:layout_alignLeft="@+id/button1"
    android:layout_below="@+id/button1"
    android:layout_marginTop="24dp"
    android:ems="10" >

    <requestFocus />
</EditText>

<EditText
    android:id="@+id/EditText2"
    android:layout_width="80dp"
    android:layout_height="60dp"
    android:layout_alignBaseline="@+id/editText1"
    android:layout_alignBottom="@+id/editText1"
    android:layout_alignLeft="@+id/button2"
    android:ems="10" />

<TextView
    android:id="@+id/TextView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignRight="@+id/editText1"
    android:layout_centerVertical="true"
    android:text="" />

<TextView
    android:id="@+id/TextView2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBottom="@+id/TextView1"
    android:layout_alignLeft="@+id/EditText2"
    android:text="" />

and logcat log file:

10-14 17:36:35.714: E/AndroidRuntime(697): FATAL EXCEPTION: main
10-14 17:36:35.714: E/AndroidRuntime(697): java.lang.IllegalStateException: Could not find a method onClick1(View) in the activity class com.example.blot.MainActivity for onClick handler on view class android.widget.Button with id 'button1'
10-14 17:36:35.714: E/AndroidRuntime(697):  at android.view.View$1.onClick(View.java:2131)
10-14 17:36:35.714: E/AndroidRuntime(697):  at android.view.View.performClick(View.java:2485)
10-14 17:36:35.714: E/AndroidRuntime(697):  at android.view.View$PerformClick.run(View.java:9080)
10-14 17:36:35.714: E/AndroidRuntime(697):  at android.os.Handler.handleCallback(Handler.java:587)
10-14 17:36:35.714: E/AndroidRuntime(697):  at android.os.Handler.dispatchMessage(Handler.java:92)
10-14 17:36:35.714: E/AndroidRuntime(697):  at android.os.Looper.loop(Looper.java:123)
10-14 17:36:35.714: E/AndroidRuntime(697):  at android.app.ActivityThread.main(ActivityThread.java:3683)
10-14 17:36:35.714: E/AndroidRuntime(697):  at java.lang.reflect.Method.invokeNative(Native Method)
10-14 17:36:35.714: E/AndroidRuntime(697):  at java.lang.reflect.Method.invoke(Method.java:507)
10-14 17:36:35.714: E/AndroidRuntime(697):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
10-14 17:36:35.714: E/AndroidRuntime(697):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
10-14 17:36:35.714: E/AndroidRuntime(697):  at dalvik.system.NativeStart.main(Native Method)
10-14 17:36:35.714: E/AndroidRuntime(697): Caused by: java.lang.NoSuchMethodException: onClick1
10-14 17:36:35.714: E/AndroidRuntime(697):  at java.lang.ClassCache.findMethodByName(ClassCache.java:247)
10-14 17:36:35.714: E/AndroidRuntime(697):  at java.lang.Class.getMethod(Class.java:962)
10-14 17:36:35.714: E/AndroidRuntime(697):  at android.view.View$1.onClick(View.java:2124)
10-14 17:36:35.714: E/AndroidRuntime(697):  ... 11 more

Answer 1

Simply try this…..

– First remove the onClick1() and onClick2() methods.

– Use Anonymous Inner class for registering and implementing the method onClick() of Interface OnClickListener

b1.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {

                          tv1.clearComposingText();
                          a=Integer.parseInt(t1.getText().toString());
                          tv1.setText(S1+=a);


            }
        });


b2.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {

                     tv2.clearComposingText();
                         b=Integer.parseInt(t2.getText().toString());
                         tv2.setText(S2+=b);

            }
        });