所以这段代码之前运行了一次。然后我关闭了我的电脑，然后在我起床时进入睡眠状态并尝试运行代码我现在在logcat中遇到错误并且应用程序崩溃了。我根本没有改变代码？怎么会发生这种情况呢？
public class DrawingView extends View{
public DrawingView(Context context) {
super(context);
// TODO Auto-generated constructor stub
}
RectF rectf = new RectF(0, 0, 200, 0);
private static final int w = 100;
public static int lastColor = Color.BLACK;
private final Random random = new Random();
private final Paint paint = new Paint();
private final int radius = 230;
private final Handler handler = new Handler();
public static int redColor = Color.RED;
public static int greenColor = Color.GREEN;
int randomWidth = 0;
int randomHeight = 0;
public static int addPoints = 0;
private final Runnable updateCircle = new Runnable() {
@Override
public void run() {
lastColor = random.nextInt(2) == 1 ? redColor : greenColor;
paint.setColor(lastColor);
invalidate();
handler.postDelayed(this, 1000);
}
};
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
handler.post(updateCircle);
}
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
handler.removeCallbacks(updateCircle);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// your other stuff here
if(random == null){
randomWidth =(int) (random.nextInt(Math.abs(getWidth()-radius/2)) + radius/2f);
randomHeight = (random.nextInt((int)Math.abs((getHeight()-radius/2 + radius/2f))));
}else {
randomWidth =(int) (random.nextInt(Math.abs(getWidth()-radius/2)) + radius/2f);
randomHeight = (random.nextInt((int)Math.abs((getHeight()-radius/2 + radius/2f))));
}
canvas.drawCircle(randomWidth, randomHeight, radius, paint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if(event.getAction() == MotionEvent.ACTION_DOWN){
int x = (int) event.getX();
int y = (int) event.getY();
if(isInsideCircle(x, y) == true){
//Do your things here
if(redColor == lastColor){
Intent i = new Intent(this.getContext(), YouFailed.class);
this.getContext().startActivity(i);
} else {
addPoints++;
}
}else {
}
}
return true;
}
public boolean isInsideCircle(int x, int y){
if ((((x - randomWidth)*(x - randomWidth)) + ((y - randomHeight)*(y - randomHeight))) < ((radius)*(radius))){
return true;
}
return false;
}
}
这是logCat中的错误。它说它与View有关？和getParent（）方法。我认为它可能与使用this而不是上下文有关，但我不确定java有时会让我感到困惑。
04-21 11:48:58.287: E/AndroidRuntime(2502): FATAL EXCEPTION: main
04-21 11:48:58.287: E/AndroidRuntime(2502): Process: com.Tripps.thesimplegame, PID: 2502
04-21 11:48:58.287: E/AndroidRuntime(2502): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.Tripps.thesimplegame/com.Tripps.thesimplegame.Main}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.ViewParent android.view.View.getParent()' on a null object reference
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.app.ActivityThread.access$800(ActivityThread.java:144)
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.os.Handler.dispatchMessage(Handler.java:102)
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.os.Looper.loop(Looper.java:135)
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.app.ActivityThread.main(ActivityThread.java:5221)
04-21 11:48:58.287: E/AndroidRuntime(2502): at java.lang.reflect.Method.invoke(Native Method)
04-21 11:48:58.287: E/AndroidRuntime(2502): at java.lang.reflect.Method.invoke(Method.java:372)
04-21 11:48:58.287: E/AndroidRuntime(2502): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
04-21 11:48:58.287: E/AndroidRuntime(2502): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
04-21 11:48:58.287: E/AndroidRuntime(2502): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.ViewParent android.view.View.getParent()' on a null object reference
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.view.ViewGroup.addViewInner(ViewGroup.java:3879)
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.view.ViewGroup.addView(ViewGroup.java:3733)
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.view.ViewGroup.addView(ViewGroup.java:3709)
04-21 11:48:58.287: E/AndroidRuntime(2502): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:406)
04-21 11:48:58.287: E/AndroidRuntime(2502): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:387)
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.app.Activity.setContentView(Activity.java:2164)
04-21 11:48:58.287: E/AndroidRuntime(2502): at com.Tripps.thesimplegame.Main.onCreate(Main.java:48)
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.app.Activity.performCreate(Activity.java:5933)
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
04-21 11:48:58.287: E/AndroidRuntime(2502): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
04-21 11:48:58.287: E/AndroidRuntime(2502): ... 10 more
public class Main extends Activity {
DrawingView v;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
//LinearLayout layout1 = new LinearLayout (this);
//FrameLayout game = new FrameLayout(this);
DrawingView v = new DrawingView (this);
//TextView myText = new TextView(this);
//Button redCircle = new Button(this);
//redCircle.setWidth(300);
//redCircle.setText(DrawingView.addPoints);
//layout1.addView(myText);
//layout1.addView(redCircle);
//redCircle.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
//game.addView(myText);
//game.addView(v);
//game.addView(layout1);
setContentView(v);
//redCircle.setOnClickListener((OnClickListener) this);
}
public void onClick(View v) {
Intent intent = new Intent(this, Main.class);
startActivity(intent);
// re-starts this activity from game-view. add this.finish(); to remove from stack
}
@Override
public boolean onCreateOptionsMenu(Menu menu){
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}