Question

I am creating sort of an app where there are many buttons with different digits each (0-9). When I click on a button I want to display its number to the edittext field. Sort of lie a calculator. Here is my code below:

public class GameActivity extends Activity {

TextView timer;
Button button1;
EditText et;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.gameactivity);
    Intent mIntent = getIntent();
    int seconds = getIntent().getIntExtra("seconds", 0);

    EditText et = (EditText) findViewById(R.id.editText1);
    final TextView timer = (TextView) findViewById(R.id.textViewtimer);
    new CountDownTimer(seconds, 1000) {

         public void onTick(long millisUntilFinished) {
             timer.setText("Seconds remaining: " + millisUntilFinished / 1000);
         }

         public void onFinish() {
             Intent intent = new Intent(GameActivity.this, Main.class);
             startActivity(intent);
         }
      }.start();
}

public void one (View v){
int n = 1;
et.setText(n);
}

Here is the error i am getting:

09-12 12:21:25.778: E/AndroidRuntime(3658): FATAL EXCEPTION: main
09-12 12:21:25.778: E/AndroidRuntime(3658): java.lang.IllegalStateException: Could not execute method of the activity
09-12 12:21:25.778: E/AndroidRuntime(3658):     at  android.view.View$1.onClick(View.java:2144)
09-12 12:21:25.778: E/AndroidRuntime(3658):     at android.view.View.performClick(View.java:2485)
09-12 12:21:25.778: E/AndroidRuntime(3658):     at android.view.View$PerformClick.run(View.java:9080)
09-12 12:21:25.778: E/AndroidRuntime(3658):     at android.os.Handler.handleCallback(Handler.java:587)
09-12 12:21:25.778: E/AndroidRuntime(3658):     at android.os.Handler.dispatchMessage(Handler.java:92)
09-12 12:21:25.778: E/AndroidRuntime(3658):     at android.os.Looper.loop(Looper.java:123)
09-12 12:21:25.778: E/AndroidRuntime(3658):     at android.app.ActivityThread.main(ActivityThread.java:3683)
09-12 12:21:25.778: E/AndroidRuntime(3658):     at java.lang.reflect.Method.invokeNative(Native Method)
09-12 12:21:25.778: E/AndroidRuntime(3658):     at   java.lang.reflect.Method.invoke(Method.java:507)
09-12 12:21:25.778: E/AndroidRuntime(3658):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
09-12 12:21:25.778: E/AndroidRuntime(3658):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
09-12 12:21:25.778: E/AndroidRuntime(3658):     at dalvik.system.NativeStart.main(Native Method)
09-12 12:21:25.778: E/AndroidRuntime(3658): Caused by: java.lang.reflect.InvocationTargetException
09-12 12:21:25.778: E/AndroidRuntime(3658):     at java.lang.reflect.Method.invokeNative(Native Method)
09-12 12:21:25.778: E/AndroidRuntime(3658):     at  java.lang.reflect.Method.invoke(Method.java:507)
09-12 12:21:25.778: E/AndroidRuntime(3658):     at  android.view.View$1.onClick(View.java:2139)
09-12 12:21:25.778: E/AndroidRuntime(3658):     ... 11 more
09-12 12:21:25.778: E/AndroidRuntime(3658): Caused by: java.lang.NullPointerException
09-12 12:21:25.778: E/AndroidRuntime(3658):     at com.dtan.mathwiz.GameActivity.one(GameActivity.java:42)
09-12 12:21:25.778: E/AndroidRuntime(3658):     ... 14 more

Answer 1

Because of this –

....
int seconds = getIntent().getIntExtra("seconds", 0);

EditText et = (EditText) findViewById(R.id.editText1);           // Already declared in global
final TextView timer = (TextView) findViewById(R.id.textViewtimer);
....

You declared your EditText globaly and initialized in onCreate with new Declaration. The method one method consider the EditText‘s object from global one only. So, it(et) is being as null. So, better remove the declaration inside of onCreate and do the code like below –

....
int seconds = getIntent().getIntExtra("seconds", 0);

et = (EditText) findViewById(R.id.editText1);
final TextView timer = (TextView) findViewById(R.id.textViewtimer);
....