java - Canvas object must be the same instance that was previously returned by lockCanvas -


i have custom surfaceview method dodraw() draws background , bitmap. problem when run error

caused by: java.lang.illegalargumentexception: canvas object must same instance returned lockcanvas

i don't see why happening. don't declare other canvases anywhere else in code. have 2 other classes, mainactivity , surfaceviewexample. mainactivity has intent open surfaceviewexample, , surfaceviewexample has method called buttons.

ourview class:

package com.thatoneprogrammerkid.gameminimum;  import android.content.context; import android.graphics.bitmap; import android.graphics.bitmapfactory; import android.graphics.canvas; import android.util.attributeset; import android.view.surfaceholder; import android.view.surfaceview;  public class ourview extends surfaceview implements surfaceholder.callback {      private surfaceholder holder;     private bitmap testimg;     public int xcoord = 500;     public int ycoord = 500;      public ourview(context context) {         super(context);         init();     }      public ourview(context context, attributeset attrs) {         super(context, attrs);         init();     }      public ourview(context context, attributeset attrs, int defstyle) {         super(context, attrs, defstyle);         init();     }      private void init() {         holder = getholder();         holder.addcallback(this);         testimg = bitmapfactory.decoderesource(getresources(),r.drawable.testimg);     }      void moveimage(int xchange, int ychange) {         xcoord += xchange;         ycoord += ychange;         dodraw();     }      void dodraw() {         canvas mycanvas = holder.lockcanvas();         if (mycanvas != null) {             mycanvas.drawargb(255, 55, 255, 255);             mycanvas.drawbitmap(testimg, xcoord, ycoord, null);         }         holder.unlockcanvasandpost(mycanvas);     }      @override     public void surfacecreated(final surfaceholder holder) {         dodraw();     }      @override     public void surfacechanged(surfaceholder holder, int format, int width, int height) {}       @override     public void surfacedestroyed(surfaceholder holder) {}  }

move unlockcanvasandpost() inside if (mycanvas != null) { statement. guess lockcanvas() returning null, , you're attempting unlock null reference.

looking @ the source code, test "is same" comes before test "is locked @ all" -- , mcanvas initialized non-null value.


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