Why is my intent not able to recognize my activity

Question

new Android Dev here. Okay so I made a simple intent to take me to another activity. The problem is that it is not able to take me to that specific activity (but it does open other activities just fine.). Here is the error it is giving me:

FATAL EXCEPTION: main
Process: com.shahrukhraza.app, PID: 5628
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.shahrukhraza.app/com.shahrukhraza.app.otherAppActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2327)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
    at android.app.ActivityThread.-wrap11(ActivityThread.java)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5417)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
    at android.support.v7.app.AppCompatDelegateImplBase.<init>(AppCompatDelegateImplBase.java:68)
    at android.support.v7.app.AppCompatDelegateImplV7.<init>(AppCompatDelegateImplV7.java:146)
    at android.support.v7.app.AppCompatDelegateImplV11.<init>(AppCompatDelegateImplV11.java:28)
    at android.support.v7.app.AppCompatDelegateImplV14.<init>(AppCompatDelegateImplV14.java:41)
    at android.support.v7.app.AppCompatDelegateImplV23.<init>(AppCompatDelegateImplV23.java:29)
    at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:188)
    at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:172)
    at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:512)
    at android.support.v7.app.AppCompatActivity.findViewById(AppCompatActivity.java:184)
    at com.shahrukhraza.app.otherAppActivity.<init>(otherAppActivity.java:14)
    at java.lang.Class.newInstance(Native Method)
    at android.app.Instrumentation.newActivity(Instrumentation.java:1067)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2317)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
    at android.app.ActivityThread.-wrap11(ActivityThread.java) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:148) 
    at android.app.ActivityThread.main(ActivityThread.java:5417)

And this is my MainActivity.java:

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_other_app);
        Button b1 = (Button) findViewById(R.id.btn1);
        b1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this, otherAppActivity.class);
                startActivity(intent);
            }
        });
    }
}

And this is the java class that is causing problems :

public class otherAppActivity extends AppCompatActivity {

    EditText eText1 = (EditText) findViewById(R.id.eText1);
    EditText eText2 = (EditText) findViewById(R.id.eText2);
    Button btn = (Button) findViewById(R.id.button);
    TextView result = (TextView)findViewById(R.id.textView);

    double n1,n2,sum;

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

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
              n1 = Double.parseDouble(eText1.getText().toString());
              n2 = Double.parseDouble(eText2.getText().toString());
                sum = n1 +n2;
                result.setText(Double.toString(sum));
            }
        });
    }
}

@MikeM. Yeah I tried to do that. Its still giving me an error. — Shahrukh Raza, May 31 '16 at 00:12
If you did indeed fix that, then your stack trace is different now. — Mike M., May 31 '16 at 00:13
All the stuff you posted from your logcat. The lines that show where the Exceptions are occurring. — Mike M., May 31 '16 at 00:18

score 0 · Answer 1 · answered May 31 '16 at 00:00

Is your otherAppActivity.class in your manifest file as a activity? Like this

<activity
        android:name=".MainActivity"
        android:label="@string/app_name"
        android:theme="@style/AppTheme.NoActionBar">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity
        android:name=".PromotionMain"
        android:label="Promotions"
        android:theme="@style/AppTheme.NoActionBar"
        >
    </activity>
    <activity
        android:name=".MyWebViewMain"
        android:label="MyWebView"
        android:theme="@style/AppTheme.NoActionBar"
        >
    </activity>

if the class is not set up in your Manifest file like this then the class will never load from a intent. You intent is set up right and should work as far as I can tell

This is my activity in the manifest /> – Shahrukh Raza May 31 '16 at 00:05 — Shahrukh Raza, May 31 '16 at 00:05

score 0 · Accepted Answer · answered May 31 '16 at 00:04

You should initilize the button and all the stuff in OnCreate or they will be null.

EditText eText1, eText2;
TextView result;
double n1,n2,sum;
Button btn;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.);
    eText1 = (EditText) findViewById(R.id.eText1);
    eText2 = (EditText) findViewById(R.id.eText2);
    btn = (Button) findViewById(R.id.button);
    result = (TextView)findViewById(R.id.textView);

    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
          n1 = Double.parseDouble(eText1.getText().toString());
          n2 = Double.parseDouble(eText2.getText().toString());
            sum = n1 +n2;
            result.setText(Double.toString(sum));
        }


    });
}

Just tried it. Same error "NullPointerException" – Shahrukh Raza May 31 '16 at 00:11 — Shahrukh Raza, May 31 '16 at 00:11

score 0 · Answer 3 · answered May 31 '16 at 00:08

0

in the otherActivity, in the setContentView you only have R.layout. without specifying the layout id. This might cause the error

answered May 31 '16 at 00:08

minh nguyen

89
3
3

Oh sorry, that was just a mistake when I was pasting it here. its fine in the actual code. – Shahrukh Raza May 31 '16 at 00:10

Why is my intent not able to recognize my activity

3 Answers3