I've been doing a little learning from youtube about android custom views and all.
In my attempt to do a Surface View (rather simple as described in this video).
I've done things pretty much in sync with what was shown in the video.
How ever I am receiving a null pointer exception in the surfaceHolder.getSurface() .
Here is my entire code :
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class MainActivity extends AppCompatActivity {
Ui ui;
Bitmap ball;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.activity_main);
ui = new Ui(this);
ball = BitmapFactory.decodeResource(getResources(), R.drawable.ball);
setContentView(ui);
}
@Override
protected void onResume() {
super.onResume();
ui.resume();
}
@Override
protected void onPause() {
super.onPause();
ui.pause();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public class Ui extends SurfaceView implements Runnable {
private Thread thread;
private SurfaceHolder surfaceHolder;
boolean ok = false;
public Ui(Context context) {
super(context);
thread = null;
surfaceHolder = getHolder();
}
@Override
public void run() {
while (ok) {
if (!surfaceHolder.getSurface().isValid()) {
continue;
}
Canvas canvas = surfaceHolder.lockCanvas();
canvas.drawARGB(200, 150, 130, 120);
canvas.drawBitmap(ball, 0, 0, null);
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
public void pause() {
ok = false;
while (true) {
try {
thread.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
break;
}
thread = null;
}
public void resume() {
ok = true;
thread = new Thread(this);
thread.run();
}
}
}
This part of the code :
Some pointer to what I am doing wrong will be helpful!.
@Override
public void run() {
while (ok) {
if (!surfaceHolder.getSurface().isValid()) {
continue;
}
Canvas canvas = surfaceHolder.lockCanvas();
canvas.drawARGB(200, 150, 130, 120);
canvas.drawBitmap(ball, 0, 0, null);
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
The problem appears in this line :
if (!surfaceHolder.getSurface().isValid())
always returns false and the later part of the code is never executed.
Logcat :
06-25 15:23:46.211 2012-2012/com.pchakraverti.canvasapp D/AndroidRuntime﹕ Shutting down VM
06-25 15:23:46.211 2012-2012/com.pchakraverti.canvasapp W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xa62f8288)
06-25 15:23:46.211 2012-2012/com.pchakraverti.canvasapp E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to resume activity {com.pchakraverti.canvasapp/com.pchakraverti.canvasapp.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2575)
at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2603)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2089)
at android.app.ActivityThread.access$600(ActivityThread.java:130)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
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:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.pchakraverti.canvasapp.Ui.run(Ui.java:44)
at java.lang.Thread.run(Thread.java:856)
at com.pchakraverti.canvasapp.Ui.resume(Ui.java:66)
at com.pchakraverti.canvasapp.MainActivity.onPostResume(MainActivity.java:24)
at android.app.Activity.performResume(Activity.java:5095)
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2565)
at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2603)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2089)
at android.app.ActivityThread.access$600(ActivityThread.java:130)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
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:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
06-25 15:23:46.227 2012-2015/com.pchakraverti.canvasapp D/dalvikvm﹕ GC_CONCURRENT freed 208K, 3% free 10919K/11207K, paused 12ms+0ms, total 15ms
06-25 15:25:15.043 2067-2067/com.pchakraverti.canvasapp D/dalvikvm﹕ Late-enabling CheckJNI
06-25 15:25:15.091 2067-2070/com.pchakraverti.canvasapp D/dalvikvm﹕ GC_CONCURRENT freed 98K, 3% free 11074K/11335K, paused 11ms+0ms, total 23ms
06-25 15:25:15.095 2067-2067/com.pchakraverti.canvasapp D/dalvikvm﹕ GC_FOR_ALLOC freed <1K, 3% free 11073K/11335K, paused 4ms, total 4ms
06-25 15:25:15.131 2067-2067/com.pchakraverti.canvasapp I/dalvikvm-heap﹕ Grow heap (frag case) to 11.887MB for 1048588-byte allocation
06-25 15:25:15.155 2067-2070/com.pchakraverti.canvasapp D/dalvikvm﹕ GC_CONCURRENT freed 0K, 3% free 12097K/12423K, paused 15ms+0ms, total 22ms
06-25 15:25:15.155 2067-2067/com.pchakraverti.canvasapp D/dalvikvm﹕ WAIT_FOR_CONCURRENT_GC blocked 0ms
06-25 15:25:15.163 2067-2067/com.pchakraverti.canvasapp I/dalvikvm﹕ Could not find method android.view.ViewGroup.onRtlPropertiesChanged, referenced from method android.support.v7.widget.Toolbar.onRtlPropertiesChanged
06-25 15:25:15.163 2067-2067/com.pchakraverti.canvasapp W/dalvikvm﹕ VFY: unable to resolve virtual method 13337: Landroid/view/ViewGroup;.onRtlPropertiesChanged (I)V
06-25 15:25:15.163 2067-2067/com.pchakraverti.canvasapp D/dalvikvm﹕ VFY: replacing opcode 0x6f at 0x0007
06-25 15:25:15.163 2067-2067/com.pchakraverti.canvasapp I/dalvikvm﹕ Could not find method android.content.res.TypedArray.getChangingConfigurations, referenced from method android.support.v7.internal.widget.TintTypedArray.getChangingConfigurations
06-25 15:25:15.163 2067-2067/com.pchakraverti.canvasapp W/dalvikvm﹕ VFY: unable to resolve virtual method 408: Landroid/content/res/TypedArray;.getChangingConfigurations ()I
06-25 15:25:15.163 2067-2067/com.pchakraverti.canvasapp D/dalvikvm﹕ VFY: replacing opcode 0x6e at 0x0002
06-25 15:25:15.167 2067-2067/com.pchakraverti.canvasapp I/dalvikvm﹕ Could not find method android.content.res.TypedArray.getType, referenced from method android.support.v7.internal.widget.TintTypedArray.getType
06-25 15:25:15.167 2067-2067/com.pchakraverti.canvasapp W/dalvikvm﹕ VFY: unable to resolve virtual method 430: Landroid/content/res/TypedArray;.getType (I)I
06-25 15:25:15.167 2067-2067/com.pchakraverti.canvasapp D/dalvikvm﹕ VFY: replacing opcode 0x6e at 0x0002
06-25 15:25:15.171 2067-2067/com.pchakraverti.canvasapp D/AndroidRuntime﹕ Shutting down VM
06-25 15:25:15.171 2067-2067/com.pchakraverti.canvasapp W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xa62f8288)
06-25 15:25:15.171 2067-2067/com.pchakraverti.canvasapp E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to resume activity {com.pchakraverti.canvasapp/com.pchakraverti.canvasapp.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2575)
at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2603)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2089)
at android.app.ActivityThread.access$600(ActivityThread.java:130)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
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:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.pchakraverti.canvasapp.Ui.run(Ui.java:45)
at java.lang.Thread.run(Thread.java:856)
at com.pchakraverti.canvasapp.Ui.resume(Ui.java:66)
at com.pchakraverti.canvasapp.MainActivity.onPostResume(MainActivity.java:24)
at android.app.Activity.performResume(Activity.java:5095)
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2565)
at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2603)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2089)
at android.app.ActivityThread.access$600(ActivityThread.java:130)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
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:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
06-25 15:26:56.039 2120-2125/com.pchakraverti.canvasapp I/dalvikvm﹕ threadid=3: reacting to signal 3
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