所以现在我遇到了这个app应用程序工作的问题但是在通过刷卡进行一些视图更改后，它会因NullPointerException而崩溃。首先 - 在onTouchListener上有一个问题。我设法让它工作，但现在我需要设法让它不崩溃（多么明显！）。
据我所知 - 找到R.id.buttons有一个问题，它基本上是ImageView，是.xml文件的一个重要组成部分（它的设置并没有在整个应用程序中改变），但经过几次刷卡我得到NullPointerException这很奇怪。
这是代码（以及后来的LogCat日志）：
public class ViewPagerAdapter extends PagerAdapter{
// Declare Variables
Context context;
int[] gim;
int[] sounds;
ArrayList<String> title;
int[] description;
LayoutInflater inflater;
View itemView;
public ViewPagerAdapter(Context context, int[] gim, ArrayList<String> title,
int[] description) {
this.context = context;
this.gim = gim;
this.title = title;
this.description = description;
}
@Override
public int getCount() {
return gim.length;
}
public int getItemPosition(Object object){
return POSITION_NONE;
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view == ((View) object);
}
@Override
public Object instantiateItem(ViewGroup container, final int position) {
// Declare Variables
final ImageView imggun;
inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
itemView = inflater.inflate(R.layout.viewpager_item, container,
false);
FrameLayout layout = (FrameLayout) itemView.findViewById(R.id.fl1);
layout.setOnTouchListener(new View.OnTouchListener() {
public boolean onTouch(View v, MotionEvent ev) {
final int action = ev.getAction();
final int evX = (int) ev.getX();
final int evY = (int) ev.getY();
switch (action) {
case MotionEvent.ACTION_DOWN:
int touchColor = getHotspotColor(R.id.buttons, evX, evY);
ColorTool ct = new ColorTool(); //line 83
int tolerance = 25;
// "Go to the party" button
if (ct.closeMatch(Color.RED, touchColor, tolerance)) {
// TODO
Log.i("ABC", "Works");
}
// "Go home" button
if (ct.closeMatch(Color.BLUE, touchColor, tolerance)) {
// TODO
Log.i("ABC", "That one too");
}
break;
case MotionEvent.ACTION_UP:
// TODO
break;
}
return true;
}
});
// Locate the ImageView in viewpager_item.xml
imggun = (ImageView) itemView.findViewById(R.id.gun);
// Capture position and set to the ImageView
imggun.setImageResource(gim[position]);
// Add viewpager_item.xml to ViewPager
((ViewPager) container).addView(itemView);
return itemView;
}
protected Context getApplicationContext() {
return null;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
// Remove viewpager_item.xml from ViewPager
((ViewPager) container).removeView((FrameLayout) object);
FrameLayout layout = (FrameLayout) object;
((ViewPager) container).removeView(layout);
}
public int getHotspotColor(int hotspotId, int x, int y) {
ImageView img = (ImageView) itemView.findViewById(hotspotId);
img.setDrawingCacheEnabled(true);
Bitmap hotspots = Bitmap.createBitmap(img.getDrawingCache());
img.setDrawingCacheEnabled(false); //line 152
return hotspots.getPixel(x, y);
}
public class ColorTool {
public boolean closeMatch(int color1, int color2, int tolerance) {
if ((int) Math.abs(Color.red(color1) - Color.red(color2)) > tolerance)
return false;
if ((int) Math.abs(Color.green(color1) - Color.green(color2)) > tolerance)
return false;
if ((int) Math.abs(Color.blue(color1) - Color.blue(color2)) > tolerance)
return false;
return true;
} // end match
}
}
LogCat日志：
12-18 07:30:14.219: E/InputEventReceiver(20187): Exception dispatching input event.
12-18 07:30:14.219: E/MessageQueue-JNI(20187): Exception in MessageQueue callback: handleReceiveCallback
12-18 07:30:14.228: E/MessageQueue-JNI(20187): java.lang.NullPointerException
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.graphics.Bitmap.createBitmap(Bitmap.java:639)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at pl.dajsiezlapac.apka.ViewPagerAdapter.getHotspotColor(ViewPagerAdapter.java:154)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at pl.dajsiezlapac.apka.ViewPagerAdapter$1.onTouch(ViewPagerAdapter.java:78)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.View.dispatchTouchEvent(View.java:7731)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2212)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1945)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2218)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2218)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2218)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2218)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2218)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2068)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1515)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.app.Activity.dispatchTouchEvent(Activity.java:2466)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2016)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.View.dispatchPointerEvent(View.java:7916)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4023)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3902)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3452)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3502)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3471)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3578)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3479)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3635)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3452)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3502)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3471)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3479)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3452)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5657)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5588)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5559)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5737)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.os.MessageQueue.nativePollOnce(Native Method)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.os.MessageQueue.next(MessageQueue.java:138)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.os.Looper.loop(Looper.java:123)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at android.app.ActivityThread.main(ActivityThread.java:5086)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at java.lang.reflect.Method.invokeNative(Native Method)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at java.lang.reflect.Method.invoke(Method.java:515)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
12-18 07:30:14.228: E/MessageQueue-JNI(20187): at dalvik.system.NativeStart.main(Native Method)
12-18 07:30:14.230: D/AndroidRuntime(20187): Shutting down VM
12-18 07:30:14.230: W/dalvikvm(20187): threadid=1: thread exiting with uncaught exception (group=0x41704d40)
12-18 07:30:14.238: E/AndroidRuntime(20187): FATAL EXCEPTION: main
12-18 07:30:14.238: E/AndroidRuntime(20187): Process: pl.dajsiezlapac.apka, PID: 20187
12-18 07:30:14.238: E/AndroidRuntime(20187): java.lang.NullPointerException
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.graphics.Bitmap.createBitmap(Bitmap.java:639)
12-18 07:30:14.238: E/AndroidRuntime(20187): at pl.dajsiezlapac.apka.ViewPagerAdapter.getHotspotColor(ViewPagerAdapter.java:154)
12-18 07:30:14.238: E/AndroidRuntime(20187): at pl.dajsiezlapac.apka.ViewPagerAdapter$1.onTouch(ViewPagerAdapter.java:78)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.View.dispatchTouchEvent(View.java:7731)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2212)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1945)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2218)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2218)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2218)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2218)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2218)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1917)
12-18 07:30:14.238: E/AndroidRuntime(20187): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2068)
12-18 07:30:14.238: E/AndroidRuntime(20187): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1515)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.app.Activity.dispatchTouchEvent(Activity.java:2466)
12-18 07:30:14.238: E/AndroidRuntime(20187): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2016)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.View.dispatchPointerEvent(View.java:7916)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:4023)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3902)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3452)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3502)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3471)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3578)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3479)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3635)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3452)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3502)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3471)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3479)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3452)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5657)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5588)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5559)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5737)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.os.MessageQueue.nativePollOnce(Native Method)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.os.MessageQueue.next(MessageQueue.java:138)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.os.Looper.loop(Looper.java:123)
12-18 07:30:14.238: E/AndroidRuntime(20187): at android.app.ActivityThread.main(ActivityThread.java:5086)
12-18 07:30:14.238: E/AndroidRuntime(20187): at java.lang.reflect.Method.invokeNative(Native Method)
12-18 07:30:14.238: E/AndroidRuntime(20187): at java.lang.reflect.Method.invoke(Method.java:515)
12-18 07:30:14.238: E/AndroidRuntime(20187): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
12-18 07:30:14.238: E/AndroidRuntime(20187): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
12-18 07:30:14.238: E/AndroidRuntime(20187): at dalvik.system.NativeStart.main(Native Method)