我最近启动了Android应用程序开发，但遇到了我正在尝试制作的应用程序的问题。每当我在模拟器中加载应用程序（确切地说是Android 4.2.2 4.00“屏幕）时，它只是说”不幸的是，俄罗斯轮盘已停止工作。“ 这是我的主要活动代码：
package com.sabexus.russianroulette;
import java.util.Random;
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
public class MainGameActivity extends Activity{
boolean ReadyToFire;
int Round;
Random Dice = new Random();
int BulletChamber;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_game);
final TextView HintTxt = (TextView) findViewById(R.id.LabelHint);
final ImageView barrelImage = (ImageView) findViewById(R.id.Barrel);
final ImageView barrelSpinningImage = (ImageView) findViewById(R.id.BarrelSpinning);
final Button TriggerBtn = (Button)findViewById(R.id.trigger);
final Button ResetBtn = (Button)findViewById(R.id.ResetButton);
barrelImage.setVisibility(View.VISIBLE);
barrelSpinningImage.setVisibility(View.GONE);
//variables
BulletChamber = 1+Dice.nextInt(6);
Round = 1;
ReadyToFire = false;
//Trigger button properties.
TriggerBtn.setVisibility(View.VISIBLE);
TriggerBtn.setBackgroundColor(Color.TRANSPARENT);
//Swipe and button touch handlers
//Trigger Button
TriggerBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
}
});
//Reset button
ResetBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
HintTxt.setText("@string/hint");
Round = 1;
ResetBtn.setVisibility(View.GONE);
}
});
//gestures
barrelImage.setOnTouchListener(new OnSwipeTouchListener() {
public boolean onSwipeTop() {
Toast.makeText(MainGameActivity.this, "top", Toast.LENGTH_SHORT).show();
return true;
}
public boolean onSwipeRight() {
if(Round!=7){
if(ReadyToFire == true){
barrelImage.setVisibility(View.GONE);
barrelSpinningImage.setVisibility(View.VISIBLE);
}
}
return true;
}
public boolean onSwipeLeft() {
Toast.makeText(MainGameActivity.this, "left", Toast.LENGTH_SHORT).show();
return true;
}
public boolean onSwipeBottom() {
Toast.makeText(MainGameActivity.this, "bottom", Toast.LENGTH_SHORT).show();
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_game, menu);
return true;
}
};
这是OnTouchSwipeListener：
package com.sabexus.russianroulette;
import android.view.GestureDetector;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
public class OnSwipeTouchListener implements OnTouchListener {
@SuppressWarnings("deprecation")
private final GestureDetector gestureDetector = new GestureDetector(new GestureListener());
public boolean onTouch(final View v, final MotionEvent event) {
return gestureDetector.onTouchEvent(event);
}
private final class GestureListener extends SimpleOnGestureListener {
private static final int SWIPE_THRESHOLD = 100;
private static final int SWIPE_VELOCITY_THRESHOLD = 100;
@Override
public boolean onDown(MotionEvent e) {
return super.onDown(e);
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
boolean result = false;
try {
float diffY = e2.getY() - e1.getY();
float diffX = e2.getX() - e1.getX();
if (Math.abs(diffX) > Math.abs(diffY)) {
if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
if (diffX > 0) {
result = onSwipeRight();
} else {
result = onSwipeLeft();
}
}
} else {
if (Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {
if (diffY > 0) {
result = onSwipeBottom();
} else {
result = onSwipeTop();
}
}
}
} catch (Exception exception) {
exception.printStackTrace();
}
return result;
}
}
public boolean onSwipeRight() {
return false;
}
public boolean onSwipeLeft() {
return false;
}
public boolean onSwipeTop() {
return false;
}
public boolean onSwipeBottom() {
return false;
}
}
这是我的Android Manifest XML：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.sabexus.russianroulette"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@android:style/Theme.NoTitleBar.Fullscreen" >
<activity
android:name="com.sabexus.russianroulette.MainGameActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
最后，听到我的主要活动XML：
<ImageView
android:id="@+id/Barrel"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_marginRight="67dp"
android:layout_marginTop="192dp"
android:src="@drawable/barrel"
android:contentDescription="@string/desc" />
<ImageView
android:id="@+id/BarrelSpinning"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_marginRight="67dp"
android:layout_marginTop="192dp"
android:src="@drawable/barrel_spinning"
android:contentDescription="@string/desc" />
<TextView
android:id="@+id/LabelHint"
android:layout_width="254dp"
android:layout_height="88dp"
android:layout_centerHorizontal="true"
android:gravity="center"
android:text="@string/hint"
android:textAppearance="?android:attr/textAppearanceMedium" />
<Button
android:id="@+id/ResetButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignRight="@+id/LabelHint"
android:layout_below="@+id/LabelHint"
android:text="@string/button"
android:visibility="gone" />
<Button
android:id="@+id/trigger"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/Barrel"
android:layout_marginBottom="32dp"
android:layout_marginRight="16dp"
android:layout_toLeftOf="@+id/Barrel"
android:text=" " />
</RelativeLayout>
另外，听到的是我的logcat日志：
05-17 17:37:35.744: E/Trace(1094): error opening trace file: No such file or directory (2)
05-17 17:37:35.862: D/AndroidRuntime(1094): Shutting down VM
05-17 17:37:35.862: W/dalvikvm(1094): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
05-17 17:37:35.884: E/AndroidRuntime(1094): FATAL EXCEPTION: main
05-17 17:37:35.884: E/AndroidRuntime(1094): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.sabexus.russianroulette/com.sabexus.russianroulette.MainGameActivity}: java.lang.NullPointerException
05-17 17:37:35.884: E/AndroidRuntime(1094): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2106)
05-17 17:37:35.884: E/AndroidRuntime(1094): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
05-17 17:37:35.884: E/AndroidRuntime(1094): at android.app.ActivityThread.access$600(ActivityThread.java:141)
05-17 17:37:35.884: E/AndroidRuntime(1094): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
05-17 17:37:35.884: E/AndroidRuntime(1094): at android.os.Handler.dispatchMessage(Handler.java:99)
05-17 17:37:35.884: E/AndroidRuntime(1094): at android.os.Looper.loop(Looper.java:137)
05-17 17:37:35.884: E/AndroidRuntime(1094): at android.app.ActivityThread.main(ActivityThread.java:5041)
05-17 17:37:35.884: E/AndroidRuntime(1094): at java.lang.reflect.Method.invokeNative(Native Method)
05-17 17:37:35.884: E/AndroidRuntime(1094): at java.lang.reflect.Method.invoke(Method.java:511)
05-17 17:37:35.884: E/AndroidRuntime(1094): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
05-17 17:37:35.884: E/AndroidRuntime(1094): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
05-17 17:37:35.884: E/AndroidRuntime(1094): at dalvik.system.NativeStart.main(Native Method)
05-17 17:37:35.884: E/AndroidRuntime(1094): Caused by: java.lang.NullPointerException
05-17 17:37:35.884: E/AndroidRuntime(1094): at android.app.Activity.findViewById(Activity.java:1839)
05-17 17:37:35.884: E/AndroidRuntime(1094): at com.sabexus.russianroulette.MainGameActivity.<init>(MainGameActivity.java:22)
05-17 17:37:35.884: E/AndroidRuntime(1094): at java.lang.Class.newInstanceImpl(Native Method)
05-17 17:37:35.884: E/AndroidRuntime(1094): at java.lang.Class.newInstance(Class.java:1319)
05-17 17:37:35.884: E/AndroidRuntime(1094): at android.app.Instrumentation.newActivity(Instrumentation.java:1054)
05-17 17:37:35.884: E/AndroidRuntime(1094): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2097)
05-17 17:37:35.884: E/AndroidRuntime(1094): ... 11 more
很抱歉这篇长篇大论，但我真的无法找出它的错误:(提前致谢：D
答案 0 :(得分：3)
移动此代码
TextView HintTxt = (TextView) findViewById(R.id.LabelHint);
ImageView barrelImage = (ImageView) findViewById(R.id.Barrel);
ImageView barrelSpinningImage = (ImageView) findViewById(R.id.BarrelSpinning);
Button TriggerBtn = (Button)findViewById(R.id.trigger);
Button ResetBtn = (Button)findViewById(R.id.ResetButton);
onCreate之后的setContentView内部。
因为您可以在布局通胀发生后引用视图。 SetContentView实际上是布局膨胀发生的地方