In Eclipse Avd I Get A "unfortunately, Calculator Has Stopped." Api Level 16

My test application is called Calculator, but I get an 'Unfortunately, Calculator has stopped.' error in AVD. I'm running my Android Virtual Device with API Level 16. This is my co

Solution 1:

Your problem most likely lies with the global View variables. Modify

TextViewanswer= (TextView) findViewById(R.id.answer);

    ButtonButtonEquals= (Button) findViewById(R.id.ButtonEquals);

so it is just

TextView answer;
Button ButtonEquals;

Then in onCreate(), do this:

@OverridepublicvoidonCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    answer = (TextView) findViewById(R.id.answer);
    ButtonEquals = (Button) findViewById(R.id.ButtonEquals);
    }

Your app is probably crashing because of the fact that you are trying to access the Views before the Activity has anything to show. Putting your code after setContentView allows the Views to be found and you avoid NullPointerExceptions

Also:

Your methods need to be methodName (View view) if they are referenced from the onClick: attribute

Most your methods need to be changed, but I'll take the ButtonEquals as an example. Your xml says

android:onClick = "equals"

So the method in your code needs to be

publicvoidequals(View v)

Adding the View argument needs to be done for every method that the onClick: attribute uses.

Solution 2:

1/ You can see exactly what's wrong by reading the logcat. It can be seen from Eclipse from the Java perspective or by using the command line:

adb logcat

2/ Move the instantiation of the *TextView*s to the onCreate() method after the setContentView() call.