Soft Keyboard getting NullPointerException when calling canvas.drawtext

StackOverflow https://stackoverflow.com/questions/19464703

Domanda

I am working on SoftKeyboard where i need to display text on keys as shown below by red blocks

enter image description here

As given in this reference and this reference, I am using below code,

 protected void onDraw(Canvas canvas) {
        if (canvas != null) {
            super.onDraw(canvas);
        }

        Paint paint = new Paint();
        paint.setTextSize(15);
        paint.setColor(Color.RED);

        int x2 = 0;
        int y2 = 0;
        int width = 0;
        List<Key> keys = SoftKeyboard.currentKeyboard.getKeys();
        for(Key key: keys) {
        if(key.codes[0] == 113)
            x2 = key.x; // value of x2 = 0;
            y2 = key.y; // value of y2 = 0;
            width = key.width; // value of width = 32;
            canvas.drawText("1", x2 + (width/2), y2 + 5, paint); // getting null pointer exception here line 240
        }
    }

My stack trace is shown below

> FATAL EXCEPTION: main java.lang.NullPointerException at com.example.android.softkeyboard.CandidateView.onDraw(CandidateView.java:240) at com.example.android.softkeyboard.CandidateView.setSuggestions(CandidateView.java:279) at com.example.android.softkeyboard.SoftKeyboard.setSuggestions(SoftKeyboard.java:597) at com.example.android.softkeyboard.SoftKeyboard.updateCandidates(SoftKeyboard.java:582) at com.example.android.softkeyboard.SoftKeyboard.onFinishInput(SoftKeyboard.java:260) at android.inputmethodservice.InputMethodService.doFinishInput(InputMethodService.java:1543) at android.inputmethodservice.InputMethodService.doStartInput(InputMethodService.java:1552) at android.inputmethodservice.InputMethodService$InputMethodImpl.startInput(InputMethodService.java:390) at android.inputmethodservice.IInputMethodWrapper.executeMessage(IInputMethodWrapper.java:158) at com.android.internal.os.HandlerCaller$MyHandler.handleMessage(HandlerCaller.java:61) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:153) at android.app.ActivityThread.main(ActivityThread.java:5000) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584) at dalvik.system.NativeStart.main(Native Method) 10-19 13:26:04.844: E/Trace(17693): error opening trace file: No such file or directory (2)

I have checked when i am debugging code the canvas is always null, so I think i am getting this exception due to canvas is null.

So i am getting this exception due to canvas is null or problem lies anywhere else.

And one thing more i have also tried using popupCharacters and this is working but i need 3 characters on key as shown below,

enter image description here

That's why i am trying to do with paint on canvas but getting exception.

È stato utile?

Soluzione 2

By mistake i am extending View class in my class. So then i extended KeyboardView as i working with LatinKeyboard which solves my issue.

Altri suggerimenti

Clearly canvas is being passed as null. The problem is where the function you posted is getting called from. This is potentially also causing you problems:

if (canvas != null) {
    super.onDraw(canvas);
}

You avoid calling the parent if canvas is null, but you don't handle the rest of your code differently? At the very least, I would put the rest of your code inside this conditional block and when canvas is null allow nothing to happen.

NO need to draw it,There is simple way of achieving this .. See detail here.

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