發生空指針異常錯誤

我試圖製作一個使用麥克風移動圖像的應用程序。 BUt我得到這個錯誤。以下是課程和LogCat。誰能幫我？謝謝！ ................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. ...........發生空指針異常錯誤

這裏是類MoveBalloon

package com.example.prova1; 

import android.app.Activity; 
import android.content.Context; 
import android.content.res.Resources; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Rect; 
import android.os.Bundle; 
import android.view.SurfaceHolder; 
import android.view.SurfaceView; 

public class MoveBalloon extends Activity { 
Bitmap balloon; 
DrawBalloon myView; 
float x,y,sensorX, sensorY; 
Microphone mic; 



public class DrawBalloon extends SurfaceView implements Runnable { 

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

public DrawBalloon(Context context) { 
    super(context); 
    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(); 

    canvas.drawColor(Color.WHITE); 
    updateMic(); 

    canvas.drawBitmap(balloon, sensorX, sensorY,null); 
    ourHolder.unlockCanvasAndPost(canvas); 
    } 
} 
} 



@Override 
protected void onCreate(Bundle savedInstanceState) { 
// TODO Auto-generated method stub 
super.onCreate(savedInstanceState); 
mic = new Microphone(); 
balloon = BitmapFactory.decodeResource(getResources(), R.drawable.images); 
sensorX=150; 
sensorY=350; 
myView= new DrawBalloon (this); 
myView.resume(); 
} 


public void updateMic(){ 
int level = mic.getLevel(); 
sensorX=0; 
sensorY=level; 
} 



}

的logcat的是在這裏：

09-21 23:57:10.909: D/ActivityThread(30461): setTargetHeapUtilization:0.25 
09-21 23:57:10.909: D/ActivityThread(30461): setTargetHeapIdealFree:8388608 
09-21 23:57:10.919: D/ActivityThread(30461): setTargetHeapConcurrentStart:2097152 
09-21 23:57:11.109: W/SurfaceView(30461): CHECK surface infomation creating=true formatChanged=true sizeChanged=true visible=true visibleChanged=true surfaceChanged=false realSizeChanged=true redrawNeeded=true left=false top=false 
09-21 23:57:11.519: I/System.out(30461): 0 
09-21 23:57:11.519: W/dalvikvm(30461): threadid=12: thread exiting with uncaught exception (group=0x41bb5438) 
09-21 23:57:11.519: E/AndroidRuntime(30461): FATAL EXCEPTION: Thread-2034 
09-21 23:57:11.519: E/AndroidRuntime(30461): java.lang.NullPointerException 
09-21 23:57:11.519: E/AndroidRuntime(30461): at com.example.prova1.MoveBalloon$DrawBalloon.run(MoveBalloon.java:64) 
09-21 23:57:11.519: E/AndroidRuntime(30461): at java.lang.Thread.run(Thread.java:856) 
09-21 23:57:11.589: W/SurfaceView(30461): CHECK surface infomation creating=false formatChanged=false sizeChanged=false visible=false visibleChanged=true surfaceChanged=false realSizeChanged=false redrawNeeded=false left=false top=false 
09-21 23:57:11.619: D/libEGL(30461): loaded /system/lib/egl/libEGL_adreno200.so 
09-21 23:57:11.619: D/libEGL(30461): loaded /system/lib/egl/libGLESv1_CM_adreno200.so 
09-21 23:57:11.629: D/libEGL(30461): loaded /system/lib/egl/libGLESv2_adreno200.so 
09-21 23:57:11.639: I/Adreno200-EGL(30461): <qeglDrvAPI_eglInitialize:299>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_JB_REL_2.0.3.1_RB1.04.01.01.45.000_msm8625_JB_REL_2.0.3.1_Merge_release_AU (Merge) 
09-21 23:57:11.639: I/Adreno200-EGL(30461): Build Date: 01/11/13 Fri 
09-21 23:57:11.639: I/Adreno200-EGL(30461): Local Branch: 
09-21 23:57:11.639: I/Adreno200-EGL(30461): Remote Branch: m/jb_rel_2.0.3.1 
09-21 23:57:11.639: I/Adreno200-EGL(30461): Local Patches: NONE 
09-21 23:57:11.639: I/Adreno200-EGL(30461): Reconstruct Branch: NOTHING 
09-21 23:57:11.999: D/OpenGLRenderer(30461): Enabling debug mode 0 
09-21 23:57:19.349: I/Choreographer(30461): Skipped 439 frames! The application may be doing too much work on its main thread. 
09-21 23:57:20.539: I/Process(30461): Sending signal. PID: 30461 SIG: 9

來源

2013-09-21 user2760701

哪行在你的運行方法的第64行。有一個空指針異常。 com.example.prova1.MoveBalloon $ DrawBalloon.run（MoveBalloon.java:64） – prijupaul

這是我的run方法中的第64行> canvas.drawColor（Color.WHITE）; – user2760701

我能做什麼，因爲我正在嘗試，但我還沒有解決這個問題 – user2760701

FRM的Android文檔

開始編輯表面的像素。返回的Canvas可以用來繪製表面的位圖。 A null如果表面尚未創建或以其他方式無法編輯，則返回。您通常需要執行Callback.surfaceCreated以找出Surface何時可供使用。

因此，只有在創建表面之後，才能執行該過程。您需要爲此執行SurfaceHolder.Callback。 Further Read..

來源

2013-09-21 23:02:14 prijupaul

謝謝。我現在會嘗試 – user2760701

發生空指針異常錯誤

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