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我正在制作一个简单的安卓应用程序。当我按下主活动中的按钮时，我调用了 MoveBalloon 活动。此活动使用麦克风根据麦克风检测到的声音在屏幕上移动图像。我按下后退按钮并返回主要活动。一切都很顺利，直到我第二次按下按钮再次开始 MoveBalloon 活动。此时应用程序崩溃。我认为问题出在 MoveBallon.class 中，但我不知道出了什么问题。下面我发布 logcat 和 MoveBalloon.class。请帮我 ！先感谢您！日志猫：

09-24 14:52:20.346: E/AndroidRuntime(23075): FATAL EXCEPTION: main
09-24 14:52:20.346: E/AndroidRuntime(23075): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.prova1/com.example.prova1.MoveBalloon}: java.lang.IllegalStateException
09-24 14:52:20.346: E/AndroidRuntime(23075):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at android.app.ActivityThread.access$600(ActivityThread.java:141)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at android.os.Handler.dispatchMessage(Handler.java:99)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at android.os.Looper.loop(Looper.java:137)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at android.app.ActivityThread.main(ActivityThread.java:5103)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at java.lang.reflect.Method.invokeNative(Native Method)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at java.lang.reflect.Method.invoke(Method.java:525)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at dalvik.system.NativeStart.main(Native Method)
09-24 14:52:20.346: E/AndroidRuntime(23075): Caused by: java.lang.IllegalStateException
09-24 14:52:20.346: E/AndroidRuntime(23075):    at android.media.MediaRecorder.start(Native Method)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at com.example.prova1.Microphone.<init>(Microphone.java:29)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at com.example.prova1.MoveBalloon.onCreate(MoveBalloon.java:106)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at android.app.Activity.performCreate(Activity.java:5133)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
09-24 14:52:20.346: E/AndroidRuntime(23075):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
09-24 14:52:20.346: E/AndroidRuntime(23075):    ... 11 more

移动气球类：

package com.example.prova1;



import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.hardware.SensorManager;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class MoveBalloon extends Activity {
    Bitmap balloon;
    Bitmap background;
    Bitmap _background;
    int i,j,k;
    private MediaPlayer mp;
    Bitmap foto;
    DrawBalloon myView;
    float x,y,sensorX, sensorY;
    SensorManager sm;
    Microphone mic;
    int width, height;
    int count=0;





public class DrawBalloon extends SurfaceView implements Runnable {

    SurfaceHolder ourHolder ;
    Thread ourThread = null;
    boolean isRunning=true;

    public DrawBalloon(Context context) {
        super(context);
         mp = MediaPlayer.create(context, R.raw.yeehaaa);
        ourHolder= getHolder();

    }

    public void pause() {
        isRunning=false;
        while(true){
            try{
                ourThread.join();
            } catch (InterruptedException e){
                e.printStackTrace();
            }
            break;
        }
        ourThread=null;
    }

    public void resume(){
        isRunning=true;
        ourThread = new Thread(this);
        ourThread.start();


    }
    @Override
    public void run (){

        while(isRunning){
            if(!ourHolder.getSurface().isValid())
                continue;
            Canvas canvas = ourHolder.lockCanvas();


         if(canvas!=null){
            updateMic();
            canvas.drawBitmap(_background,0,0,null);
            canvas.drawBitmap(balloon, sensorX, sensorY,null);
            checkCollisions(canvas);
            ourHolder.unlockCanvasAndPost(canvas);
         }
        }
    }
}



@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    /*sm= (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    if(sm.getSensorList(Sensor.TYPE_ACCELEROMETER).size()!=0){
        Sensor s = sm.getSensorList(Sensor.TYPE_ACCELEROMETER).get(0);
        sm.registerListener(this,s ,SensorManager.SENSOR_DELAY_NORMAL);
    }*/
    Intent intent= getIntent();
    i=intent.getIntExtra("b1", 0);
    j=intent.getIntExtra("b2", 0);
    k=intent.getIntExtra("b3", 0);

mic = new Microphone();
balloon = BitmapFactory.decodeResource(getResources(), i);
background = BitmapFactory.decodeResource(getResources(), j);

DisplayMetrics displaymetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
height = displaymetrics.heightPixels;
width = displaymetrics.widthPixels; 
sensorX=(width-balloon.getWidth())/2;
sensorY=height-balloon.getHeight()-20;

//x=y=sensorX=sensorY=0;


_background = getResizedBitmap(background,height,width);
myView= new DrawBalloon (this);
myView.resume();
setContentView(myView);
}

public void updateMic(){
double level = mic.getAmplitudeEMA();

    sensorY-=level;
}



public Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth) {
    int width = bm.getWidth();
    int height = bm.getHeight();
    float scaleWidth = ((float) newWidth) / width;
    float scaleHeight = ((float) newHeight) / height;

    // Create a matrix for the manipulation
    Matrix matrix = new Matrix();

    // Resize the bit map
    matrix.postScale(scaleWidth, scaleHeight);

    // Recreate the new Bitmap
    Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, true);
    return resizedBitmap;
}



private void checkCollisions(Canvas canvas){

    foto=BitmapFactory.decodeResource(getResources(), k);
        if(sensorY<=50&&sensorY>=40){


           canvas.drawBitmap(foto, (width-foto.getWidth())/2, 30, null);

           mp.start();
    }else{
        if (sensorY<40){
               canvas.drawBitmap(foto,(width-foto.getWidth())/2, 30, null);

        }
    }
}



@Override
public void onBackPressed() {
    // TODO Auto-generated method stub
    mp.stop();
    finish();
    super.onBackPressed();
}
}

这是 Microphone.class ：

package com.example.prova1;
import java.io.IOException;

import android.media.MediaRecorder;

public class Microphone {
    MediaRecorder recorder;
    int level;
    static final private double EMA_FILTER = 0.6;
    private double mEMA = 0;

    public Microphone(){
        // Audio recorder
        recorder = new MediaRecorder();
        recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
        recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
        recorder.setOutputFile("/dev/null");
        mEMA = 0;
       try {
            recorder.prepare();
               recorder.start();

       }
          catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    public void stopMic(){

                recorder.release();


}
    public double getLevel(){
        level = recorder.getMaxAmplitude();
        level = level/2700;
        return level;
    }
    public double getAmplitudeEMA() {
        double amp = getLevel();
        mEMA = EMA_FILTER * amp + (1.0 - EMA_FILTER) * mEMA;
        return mEMA;
}

}

新的 LOGCAT：

09-24 16:31:44.140: E/AndroidRuntime(31331): FATAL EXCEPTION: Thread-1680
09-24 16:31:44.140: E/AndroidRuntime(31331): java.lang.NullPointerException
09-24 16:31:44.140: E/AndroidRuntime(31331):    at com.example.prova1.Microphone.getLevel(Microphone.java:43)
09-24 16:31:44.140: E/AndroidRuntime(31331):    at com.example.prova1.Microphone.getAmplitudeEMA(Microphone.java:48)
09-24 16:31:44.140: E/AndroidRuntime(31331):    at com.example.prova1.MoveBalloon.updateMic(MoveBalloon.java:157)
09-24 16:31:44.140: E/AndroidRuntime(31331):    at com.example.prova1.MoveBalloon$DrawBalloon.run(MoveBalloon.java:84)
4

1 回答 1

0

我不确定，麦克风类从何而来。你能提供更多关于这门课的信息吗？

但是问题似乎可能在麦克风类中的 MediaRecorder 初始化中，此时麦克风已经在录制。

在这里，您可以了解如何使用 MediaRecorder: Audio Capture正确处理音频录制。

有关实时音频处理，请参阅实时音频捕获。

通常，当按下后退按钮时，您必须停止并释放媒体记录器。这允许您稍后启动记录器而不会出错。

希望这会有所帮助。

于 2013-09-24T14:14:59.990 回答