Android 当触摸屏打开时，OnTouchEvent（）程序退出

我有一个程序，基本上当你触摸屏幕时需要停止“人” 只从左向右移动的人

我的个人课

package com.example.pedestriancrossing2;

公共阶层人士{

private float x,y;
private int height,width;
private int screenWidth;
private int destination;
private boolean needStop;
private float tempX;
public Person (float x, float y, int height, int width, int screenW)
{
    this.x = x;
    this.y = y;
    this.height = height;
    this.width = width;
    this.screenWidth = screenW;
    this.destination = -1;

}
public float left()
{
    return x-width;
}
public float right()
{
    return x+width;
}
public float Top()
{
    return y-height;
}
public float Bottom()
{
    return y+height;
}

public void setDestination (int destination)
{
    this.destination = destination;
}
public void movePerson ()
{

    if(right()>=screenWidth)
    {
        x = 0;
    }
    if(destination == -1)
        x++;



}

}

和我的主要活动>>

package com.example.pedestriancrossing2;

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.annotation.SuppressLint;
import android.graphics.Point;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import android.app.Activity;
import android.view.View.OnTouchListener;
import android.util.Log;

public class MainActivity extends ActionBarActivity {

private Person person;
@SuppressLint("NewApi") @Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    Point p = new Point();
    this.getWindowManager().getDefaultDisplay().getSize(p);
    int screenWidth = p.x;
    int screenHeigh = p.y;
    Car car = new Car( screenWidth/2 , screenHeigh/2 , 15 , screenHeigh);
    Person person = new Person( 0 , screenHeigh/2 , 10 , 20 , screenWidth);
    CarView carview = new CarView(this, car);
    PersonView personview = new PersonView(this, person);
    GameView gameview = new GameView(this);
    gameview.setViews(carview, personview);
    setContentView(gameview);
    CarMover moveCar = new CarMover(car,gameview);
    PersonMover movePerson = new PersonMover(person, gameview);

    person.setDestination(-1);
    moveCar.start();
    movePerson.start();
    /*setContentView(R.layout.activity_main);*/

    /*if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment())
                .commit();
    }*/
}
    public boolean onTouchEvent(MotionEvent event)
{
    if (person != null) return false;
    int destination = event.getAction();
    if(destination == MotionEvent.ACTION_DOWN)
    {
        person.setDestination(1);
    }
    if(destination == MotionEvent.ACTION_UP)
    {
        person.setDestination(-1);
    }
    return true;
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.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();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container, false);
        return rootView;
    }
}

/*@Override*/
/*public boolean onTouch(View v, MotionEvent event) {
    // TODO Auto-generated method stub

    int isTouched;
    isTouched = event.getAction();
    if(isTouched == MotionEvent.ACTION_DOWN)
    {
        person.setNeedStop(true);
    }
    if(isTouched == MotionEvent.ACTION_UP)
    {
        person.setNeedStop(false);
    }

    return true;


}*/

}

日志：

03-30 13:57:45.092: E/AndroidRuntime(856): java.lang.NullPointerException
03-30 13:57:45.092: E/AndroidRuntime(856):  at com.example.pedestriancrossing2.MainActivity.onTouchEvent(MainActivity.java:57)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.app.Activity.dispatchTouchEvent(Activity.java:2461)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.support.v7.app.ActionBarActivityDelegateICS$WindowCallbackWrapper.dispatchTouchEvent(ActionBarActivityDelegateICS.java:260)
03-30 13:57:45.092: E/AndroidRuntime(856):  at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2016)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.View.dispatchPointerEvent(View.java:7886)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:3954)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3833)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3399)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3449)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3418)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3525)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3426)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3582)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3399)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3449)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3418)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3426)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3399)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5602)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5582)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5553)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5682)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.os.MessageQueue.nativePollOnce(Native Method)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.os.MessageQueue.next(MessageQueue.java:138)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.os.Looper.loop(Looper.java:123)
03-30 13:57:45.092: E/AndroidRuntime(856):  at android.app.ActivityThread.main(ActivityThread.java:5017)
03-30 13:57:45.092: E/AndroidRuntime(856):  at java.lang.reflect.Method.invokeNative(Native Method)
03-30 13:57:45.092: E/AndroidRuntime(856):  at java.lang.reflect.Method.invoke(Method.java:515)
03-30 13:57:45.092: E/AndroidRuntime(856):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
03-30 13:57:45.092: E/AndroidRuntime(856):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
03-30 13:57:45.092: E/AndroidRuntime(856):  at dalvik.system.NativeStart.main(Native Method)

---

确定要解决您的问题，您应该确保

person

引用类的实例

范例

person = new Person();

在

onCreate

中。Person是一个例子，随班级一起改变它

在为其分配实例之前，不能使用

person

---

换成它

public boolean onTouchEvent(MotionEvent event)
{
    if (person != null) return false;
    int destination = event.getAction();
    if(destination == MotionEvent.ACTION_DOWN)
    {
        person.setDestination(1);
    }
    if(destination == MotionEvent.ACTION_UP)
    {
        person.setDestination(-1);
    }
    return true;
}

---

可能是在

person

获取实例之前，以某种奇怪的方式调用了

onTouchEvent

。

？问题是什么？问题是当我执行程序时，一切正常，但当我触摸屏幕时，程序突然崩溃。我正在使用nexus S作为模拟器。好的，添加logcat以便我们可以帮助您。这里是日志文件的下载链接：抱歉，我无法在此处添加它。为您添加的是，您应该只添加应用程序崩溃时出现的logcat，而不是所有内容！我已经做了，但仍然不起作用。Person-Person=新用户（0，屏幕高度/2,10,20，屏幕宽度）；这是您想要的吗？是的，您添加它的地方？并确保它发生在onTouchEvent之前，或者使用

if（person==null）return false暂时避免它我可以添加person和myactivity类的所有代码，如果它有帮助的话。我现在看不出任何错误，我编辑了我的答案