当我开始这个活动时，我得到了一个空指针 exveption，我在寻找罪魁祸首时遇到了一些问题。此活动在我的清单文件中。此 Activity 依赖于三个类。其中一项活动扩展了线程类。这些课程不在我的清单中。
活动：
package com.example.soft;
import com.example.soft.util.SystemUiHider;
import android.annotation.TargetApi;
import android.app.Activity;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.Window;
import android.widget.*;
import android.widget.AdapterView.OnItemClickListener;
public class PlayGame extends Activity {
private static final boolean AUTO_HIDE = true;
private static final int AUTO_HIDE_DELAY_MILLIS = 3000;
private static final boolean TOGGLE_ON_CLICK = true;
private static final int HIDER_FLAGS = SystemUiHider.FLAG_HIDE_NAVIGATION;
private SystemUiHider mSystemUiHider;
private GraphicsMole im;
private int currentMolePos = -1;
private int scoreCurr = 0;
private int lifeCurr = 9;
private Handler step;
private Handler Update;
private MoleGame mg;
private boolean isMole = true;
private Mole mole = new Mole();
private double prob=0.7;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setRequestedOrientation(0);//Horizontal Screen Orientation
setContentView(R.layout.activity_play_game);
final View controlsView = findViewById(R.id.fullscreen_content_controls);
final View contentView = findViewById(R.id.fullscreen_content);
final TextView scoreTview = (TextView) findViewById(R.id.Score);
final TextView lifeTview = (TextView) findViewById(R.id.Life);
final GridView gw = (GridView) findViewById(R.id.gridview);
step = new ChangeImage();
Update = new Handler();
im = new GraphicsMole(this);
gw.setAdapter(im);
// ----------------------------
mSystemUiHider = SystemUiHider.getInstance(this, contentView,
HIDER_FLAGS);
mSystemUiHider.setup();
mSystemUiHider
.setOnVisibilityChangeListener(new SystemUiHider.OnVisibilityChangeListener() {
// Cached values.
int mControlsHeight;
int mShortAnimTime;
@Override
@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR2)
public void onVisibilityChange(boolean visible) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
if (mControlsHeight == 0) {
mControlsHeight = controlsView.getHeight();
}
if (mShortAnimTime == 0) {
mShortAnimTime = getResources().getInteger(
android.R.integer.config_shortAnimTime);
}
controlsView
.animate()
.translationY(visible ? 0 : mControlsHeight)
.setDuration(mShortAnimTime);
} else {
controlsView.setVisibility(visible ? View.VISIBLE
: View.GONE);
}
if (visible && AUTO_HIDE) {
delayedHide(AUTO_HIDE_DELAY_MILLIS);
}
}
});
contentView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (TOGGLE_ON_CLICK) {
mSystemUiHider.toggle();
} else {
mSystemUiHider.show();
}
}
});
gw.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, final View v,
int position, long id) {
if (currentMolePos == position) {
Update.post(new Runnable() {
@Override
public void run() {
if (isMole == true) {
scoreCurr = scoreCurr + 150;
scoreTview.setText("Score: " + scoreCurr);
scoreTview.refreshDrawableState();
if(scoreCurr==3000){
setProbability(0.60);
mg.setTimeToWait(700);
}
else if(scoreCurr==7500){
setProbability(0.45);
mg.setTimeToWait(500);
}
}
else {
lifeCurr = lifeCurr - 1;
lifeTview.setText("Life: " + lifeCurr);
lifeTview.refreshDrawableState();
if (lifeCurr == 0) {
mg.stopThread();
Intent gameOverIntent = new Intent(
PlayGame.this, GameMenu.class);
gameOverIntent.putExtra("score", scoreCurr);
startActivity(gameOverIntent);
finish();
}
}
}
});
}
}
});
mg = new MoleGame(step);
mg.start();
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Trigger the initial hide() shortly after the activity has been
// created, to briefly hint to the user that UI controls
// are available.
delayedHide(100);
}
View.OnTouchListener mDelayHideTouchListener = new View.OnTouchListener() {
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
if (AUTO_HIDE) {
delayedHide(AUTO_HIDE_DELAY_MILLIS);
}
return false;
}
};
Handler mHideHandler = new Handler();
Runnable mHideRunnable = new Runnable() {
@Override
public void run() {
mSystemUiHider.hide();
}
};
private void delayedHide(int delayMillis) {
mHideHandler.removeCallbacks(mHideRunnable);
mHideHandler.postDelayed(mHideRunnable, delayMillis);
}
public Activity getActivity(){
return this.getActivity();
}
private class ChangeImage extends Handler {
Hole hole = new Hole();
private int oldPosition = -1;
@Override
public void handleMessage(Message msg) {
Bundle bundle = msg.getData();
currentMolePos = bundle.getInt("newPosition");
if (Math.random() < prob) {
im.setItem(currentMolePos, mole.getmole());
isMole = true;
}
else {
im.setItem(currentMolePos, mole.getphone());
isMole = false;
}
if (oldPosition != -1 && currentMolePos != oldPosition) {
im.setItem(oldPosition, hole.getHole());
}
oldPosition = currentMolePos;
im.notifyDataSetChanged();
}
}
public void setProbability(double prob){
this.prob=prob;
}
}
日志猫：
10-06 18:04:46.975: E/AndroidRuntime(3636): FATAL EXCEPTION: main
10-06 18:04:46.975: E/AndroidRuntime(3636): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.quitandbefree/com.example.quitandbefree.PlayGame}: java.lang.NullPointerException
10-06 18:04:46.975: E/AndroidRuntime(3636): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1939)
10-06 18:04:46.975: E/AndroidRuntime(3636): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1960)
10-06 18:04:46.975: E/AndroidRuntime(3636): at android.app.ActivityThread.access$1500(ActivityThread.java:145)
10-06 18:04:46.975: E/AndroidRuntime(3636): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1045)
10-06 18:04:46.975: E/AndroidRuntime(3636): at android.os.Handler.dispatchMessage(Handler.java:99)
10-06 18:04:46.975: E/AndroidRuntime(3636): at android.os.Looper.loop(Looper.java:150)
10-06 18:04:46.975: E/AndroidRuntime(3636): at android.app.ActivityThread.main(ActivityThread.java:4369)
10-06 18:04:46.975: E/AndroidRuntime(3636): at java.lang.reflect.Method.invokeNative(Native Method)
10-06 18:04:46.975: E/AndroidRuntime(3636): at java.lang.reflect.Method.invoke(Method.java:507)
10-06 18:04:46.975: E/AndroidRuntime(3636): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:846)
10-06 18:04:46.975: E/AndroidRuntime(3636): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:604)
10-06 18:04:46.975: E/AndroidRuntime(3636): at dalvik.system.NativeStart.main(Native Method)
10-06 18:04:46.975: E/AndroidRuntime(3636): Caused by: java.lang.NullPointerException
10-06 18:04:46.975: E/AndroidRuntime(3636): at com.example.quitandbefree.PlayGame.onCreate(PlayGame.java:129)
10-06 18:04:46.975: E/AndroidRuntime(3636): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
10-06 18:04:46.975: E/AndroidRuntime(3636): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1891)
10-06 18:04:46.975: E/AndroidRuntime(3636): ... 11 more
编辑！XML 布局：
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/shadedbackground"
tools:context=".PlayGame" >
<!--
The primary full-screen view. This can be replaced with whatever view
is needed to present your content, e.g. VideoView, SurfaceView,
TextureView, etc.
-->
<!-- <ViewFlipper android:id="@+id/flipper"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
</ViewFlipper>
-->
<TextView android:id="@+id/Score" android:layout_width="70px"
android:layout_height="50px" android:text="Score: "
android:textColor="#FF0000" android:textStyle="bold" android:textSize="15px">
</TextView>
<TextView android:id="@+id/Life" android:layout_width="70px"
android:layout_gravity="right"
android:layout_height="50px" android:text="Life: "
android:textColor="#FF0000" android:textSize="15px" android:textStyle="bold">
</TextView>
<GridView android:id="@+id/gridview" android:numColumns="4"
android:layout_marginTop="10dp"
android:verticalSpacing="0px" android:horizontalSpacing="0px"
android:stretchMode="columnWidth" android:gravity="center"
android:layout_width="fill_parent" android:layout_height="600px">
</GridView>
<!--
This FrameLayout insets its children based on system windows using
android:fitsSystemWindows.
-->
</FrameLayout>