我正在制作一款安卓游戏，它应该会显示一条消息，表明你已失去某一点。但是，它失败的原因是我无法弄明白。在checkLivesLeftValue（）上，如果用户已经用尽了他所有的三个生命，它会调用onMethod（）。但是，当我创建一个toast时，应用程序失败了，为什么???
这是我的java代码：
import java.util.ArrayList;
import android.app.AlertDialog;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.widget.TextView;
import android.widget.Toast;
public class ExampleView extends SurfaceView implements SurfaceHolder.Callback
{
class ExampleThread extends Thread
{
private ArrayList<Parachuter> parachuters;
private Bitmap parachuter;
private Paint black;
private boolean running;
private SurfaceHolder mSurfaceHolder;
private Context mContext;
private Handler mHandler;
private GameScreenActivity mActivity;
private long frameRate;
private boolean loading;
public float x;
public float y;
public MediaPlayer mp1;
public int parachuterIndexToResetAndDelete;
public int canvasGetWidth;
public int livesLeftValue;
public ExampleThread(SurfaceHolder sHolder, Context context, Handler handler)
{
mSurfaceHolder = sHolder;
mHandler = handler;
mContext = context;
mActivity = (GameScreenActivity) context;
parachuters = new ArrayList<Parachuter>();
parachuter = BitmapFactory.decodeResource(getResources(), R.drawable.parachuteman);
black = new Paint();
black.setStyle(Paint.Style.FILL);
black.setColor(Color.WHITE);
running = true;
// This equates to 26 frames per second.
frameRate = (long) (1000 / 26);
loading = true;
}
@Override
public void run()
{
while (running)
{
Canvas c = null;
try
{
c = mSurfaceHolder.lockCanvas();
synchronized (mSurfaceHolder)
{
long start = System.currentTimeMillis();
doDraw(c);
long diff = System.currentTimeMillis() - start;
if (diff < frameRate)
Thread.sleep(frameRate - diff);
}
} catch (InterruptedException e)
{
}
finally
{
if (c != null)
{
mSurfaceHolder.unlockCanvasAndPost(c);
}
}
}
}
protected void doDraw(Canvas canvas)
{
canvas.drawRect(0, 0, canvas.getWidth(), canvas.getHeight(), black);
canvasGetWidth = canvas.getWidth();
//Draw
for (int i = 0; i < parachuters.size(); i++)
{
canvas.drawBitmap(parachuter, parachuters.get(i).getX(), parachuters.get(i).getY(), null);
parachuters.get(i).tick();
}
//Remove
for (int i = 0; i < parachuters.size(); i++)
{
if (parachuters.get(i).getY() > canvas.getHeight()) {
parachuters.remove(i);
onPlaySound();
onMethod();
checkLivesLeftValue();
}
}
}
public void onPlaySound()
{
try {
mp1 = MediaPlayer.create(getContext(), R.raw.bombsound);
mp1.start();
} catch (Exception e) {
e.printStackTrace();
mp1.release();
}
}
public void onMethod() {
Toast.makeText(getContext(), "You lost!", 15).show();
}
private void checkLivesLeftValue() {
// TODO Auto-generated method stub
if (livesLeftValue == 3) {
//Message to display: "You lost!"
onMethod();
}
else {
livesLeftValue = livesLeftValue + 1;
}
}
public boolean onTouchEvent(MotionEvent event)
{
if (event.getAction() != MotionEvent.ACTION_DOWN)
return false;
float x1 = event.getX();
float y1 = event.getY();
initiateDrawParachuters();
return true;
}
public void initiateDrawParachuters()
{
drawParachuter1();
}
private void drawParachuter1() {
// TODO Auto-generated method stub
//Parachuter nr. 1
x = 68;
y = 40;
Parachuter p = new Parachuter(x, y);
parachuters.add(p);
drawParachuter2();
}
private void drawParachuter2() {
// TODO Auto-generated method stub
//Parachuter nr. 2
x = 100;
y = 80;
Parachuter p = new Parachuter(x, y);
parachuters.add(p);
drawParachuter3();
}
private void drawParachuter3() {
// TODO Auto-generated method stub
//Parachuter nr. 3
x = 150;
y = 120;
Parachuter p = new Parachuter(x, y);
parachuters.add(p);
drawParachuter4();
}
private void drawParachuter4() {
// TODO Auto-generated method stub
//Parachuter nr. 4
x = 170;
y = 150;
Parachuter p = new Parachuter(x, y);
parachuters.add(p);
drawParachuter5();
}
private void drawParachuter5() {
// TODO Auto-generated method stub
//Parachuter nr. 5
x = 180;
y = 170;
Parachuter p = new Parachuter(x, y);
parachuters.add(p);
drawParachuter6();
}
private void drawParachuter6() {
// TODO Auto-generated method stub
//Parachuter nr. 6
x = 200;
y = 180;
Parachuter p = new Parachuter(x, y);
parachuters.add(p);
}
public void drawParachuters()
{
Parachuter p = new Parachuter(x, y);
parachuters.add(p);
Toast.makeText(getContext(), "x=" + x + " y=" + y, 15).show();
}
public void setRunning(boolean bRun)
{
running = bRun;
}
public boolean getRunning()
{
return running;
}
}
/** Handle to the application context, used to e.g. fetch Drawables. */
private Context mContext;
/** Pointer to the text view to display "Paused.." etc. */
private TextView mStatusText;
/** The thread that actually draws the animation */
private ExampleThread eThread;
public ExampleView(Context context)
{
super(context);
// register our interest in hearing about changes to our surface
SurfaceHolder holder = getHolder();
holder.addCallback(this);
// create thread only; it's started in surfaceCreated()
eThread = new ExampleThread(holder, context, new Handler()
{
@Override
public void handleMessage(Message m)
{
// mStatusText.setVisibility(m.getData().getInt("viz"));
// mStatusText.setText(m.getData().getString("text"));
}
});
setFocusable(true);
}
@Override
public boolean onTouchEvent(MotionEvent event)
{
return eThread.onTouchEvent(event);
}
public ExampleThread getThread()
{
return eThread;
}
@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3)
{
// TODO Auto-generated method stub
}
public void surfaceCreated(SurfaceHolder holder)
{
if (eThread.getState() == Thread.State.TERMINATED)
{
eThread = new ExampleThread(getHolder(), getContext(), getHandler());
eThread.start();
}
else
{
eThread.start();
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder)
{
boolean retry = true;
eThread.setRunning(false);
while (retry)
{
try
{
eThread.join();
retry = false;
}
catch (InterruptedException e)
{
}
}
}
}
这是我的logcat输出：
03-24 16:32:59.442: W/dalvikvm(363): threadid=7: thread exiting with uncaught exception (group=0x4001d800)
03-24 16:32:59.641: E/AndroidRuntime(363): FATAL EXCEPTION: Thread-8
03-24 16:32:59.641: E/AndroidRuntime(363): java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
03-24 16:32:59.641: E/AndroidRuntime(363): at android.os.Handler.<init>(Handler.java:121)
03-24 16:32:59.641: E/AndroidRuntime(363): at android.widget.Toast.<init>(Toast.java:68)
03-24 16:32:59.641: E/AndroidRuntime(363): at android.widget.Toast.makeText(Toast.java:231)
03-24 16:32:59.641: E/AndroidRuntime(363): at com.mysoftwaremobileapps.ParachuteHunter.ExampleView$ExampleThread.onMethod(ExampleView.java:135)
03-24 16:32:59.641: E/AndroidRuntime(363): at com.mysoftwaremobileapps.ParachuteHunter.ExampleView$ExampleThread.doDraw(ExampleView.java:116)
03-24 16:32:59.641: E/AndroidRuntime(363): at com.mysoftwaremobileapps.ParachuteHunter.ExampleView$ExampleThread.run(ExampleView.java:79)
03-24 16:33:03.842: I/Process(363): Sending signal. PID: 363 SIG: 9
答案 0 :(得分：0)
您正在从Thread创建一个Toast，它没有附加Looper。最简单的解决方案是从UI线程创建Toast，默认情况下使用Looper。
此外，您已经拥有一个在View构造函数中创建的Handler。您可以使用此Handler将一些Runnable发布到UI线程并在那里创建Toast。
public void onMethod() {
mHandler.post(new Runnable() {
@Override
public void run() {
Toast.makeText(getContext(), "You lost!", 15).show();
}
});
}