CODEWITHSUNDEEP
androidnullpointerexception
user2163853
user2163853

Reputation: 917

NullPointerException - can't figure out what's null

I have the following code that creates some views dynamically:

        for (int i = 0; i < z; i++) {
            LayoutInflater vi = (LayoutInflater) getApplicationContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            View v = vi.inflate(R.layout.tag_table_row, null); //this is the template for each view

            // set xyz dynamically
            TextView textView = (TextView) v.findViewById(R.id.xyz); //id within the layout 
            textView.setText(xyz[i]);
            //set score dynamically
            TextView textView2 = (TextView) v.findViewById(R.id.score);
            textView2.setText(scores[i]);
            //set bar graph dynamically
            TagBar tagBar = (TagBar) findViewById(R.id.tagbar);
            double tag1score = Double.parseDouble(scores[i]);
            Log.i("score", scores[i]);
            double factor = 250;
            double len = tag1score*factor;
            int length = (int) len;
            Log.i("length", Integer.toString(length));
            tagBar.setBarLength(length);                

            // insert into main view
            View insertPoint = findViewById(R.id.tagTable);
            ((ViewGroup) insertPoint).addView(v, i, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.FILL_PARENT));
        }

TagBar is a class I created that basically draws a horizontal bar with a length that is determined by the "score". All of this code works fine, except for the line tagBar.setBarLength(length);. When this line runs, I get a NullPointerException and the app crashes.

As far as I know, length is defined and is not null, tagBar is defined and is not null, and the setBarLength() method is defined within the TagBar class. Why am I getting a NullPointerException`?

setBarLength() is defined in the TagBar class like so:

    public void setBarLength(int n) {
    barLeng = n;
    invalidate();
    requestLayout();
}

Here's my Logcat:

07-20 12:33:52.029: E/AndroidRuntime(8075): FATAL EXCEPTION: main
07-20 12:33:52.029: E/AndroidRuntime(8075): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.tforan.blobtag4/com.tforan.blobtag4.PlaceActivity}: java.lang.NullPointerException
07-20 12:33:52.029: E/AndroidRuntime(8075):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1852)
07-20 12:33:52.029: E/AndroidRuntime(8075):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1873)
07-20 12:33:52.029: E/AndroidRuntime(8075):     at android.app.ActivityThread.access$1500(ActivityThread.java:135)
07-20 12:33:52.029: E/AndroidRuntime(8075):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1054)
07-20 12:33:52.029: E/AndroidRuntime(8075):     at android.os.Handler.dispatchMessage(Handler.java:99)
07-20 12:33:52.029: E/AndroidRuntime(8075):     at android.os.Looper.loop(Looper.java:150)
07-20 12:33:52.029: E/AndroidRuntime(8075):     at android.app.ActivityThread.main(ActivityThread.java:4358)
07-20 12:33:52.029: E/AndroidRuntime(8075):     at java.lang.reflect.Method.invokeNative(Native Method)
07-20 12:33:52.029: E/AndroidRuntime(8075):     at java.lang.reflect.Method.invoke(Method.java:507)
07-20 12:33:52.029: E/AndroidRuntime(8075):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:849)
07-20 12:33:52.029: E/AndroidRuntime(8075):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:607)
07-20 12:33:52.029: E/AndroidRuntime(8075):     at dalvik.system.NativeStart.main(Native Method)
07-20 12:33:52.029: E/AndroidRuntime(8075): Caused by: java.lang.NullPointerException
07-20 12:33:52.029: E/AndroidRuntime(8075):     at com.tforan.blobtag4.PlaceActivity.onCreate(PlaceActivity.java:169)
07-20 12:33:52.029: E/AndroidRuntime(8075):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1072)
07-20 12:33:52.029: E/AndroidRuntime(8075):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1816)
07-20 12:33:52.029: E/AndroidRuntime(8075):     ... 11 more

Any help would be greatly appreciated. Thanks!

Upvotes: 1

Views: 91

Answers (2)

Tarsem Singh
Tarsem Singh

Reputation: 14199

check here TagBar tagBar = (TagBar) findViewById(R.id.tagbar);

you are getting java.lang.NullPointerException

because your tagBar object is null !

Upvotes: 2

Gabe Sechan
Gabe Sechan

Reputation: 93726

A null pointer exception is generated when you dereference a null pointer- when something to the left of a . is null. So the only thing that could cause it is tagbar being null, assuming you have the right line. I'd make sure that the id you're searching for is actually in your xml. If it really is, then I'd run it under a debugger.

Edit: did you mean to search for the tagbar in the activity's view, rather than in the view you inflate in the loop? That seems likely to be the bug. All the other finds are v.findViewById, this one is just findViewById.

Upvotes: 4

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