Android Onclick上出错，java.lang.IllegalStateException:无法执行活动的方法

每次单击“撤消”和“重做”时都会出现错误，我不知道为什么会出现此错误

java.lang.IllegalStateException: Could not execute method of the activity.

谁能帮我一下吗。 提前谢谢。 下面是我的代码及其错误日志

--绘画课

public class Draw extends Activity implements {

public static String filex;

private static final int SELECT_PICTURE = 1;

public static String selectedImagePath;
public static Bitmap cBitmap;

public static Integer resize;
public static Integer imageBackgroundEraser;
// Instance variables

public static Paint       mPaint;
private MaskFilter  mEmboss;
private MaskFilter  mBlur;
private MyView      mView;
private int mImageCount = 0;
private int mLastBg = 0;

public static Integer WW;
public static Integer WH;

private float BrushWidth; 
private int  thickness;
private int BrushColor;
public static int backgroundColor; 
float Mx1,My1;
float x,y;

@SuppressWarnings("deprecation")
@Override

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_draw);

    Display display = getWindowManager().getDefaultDisplay(); //***


    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_draw4_fun_main);

    Display display = getWindowManager().getDefaultDisplay(); //***

    WH = display.getHeight();  //***
    WW = display.getWidth();  //***

    final MyView myView = new MyView(this);
    frm_layout=(FrameLayout) findViewById(R.id.main_frame);
    frm_layout.addView(myView);


    setInitialPaint();
    backgroundColor = Color.WHITE;

}

private void setInitialPaint() {
    //bgColor = 0xFFFFFFFF; // default bg color white
    BrushWidth = 3;
    BrushColor = 0xFF000000; //**
    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setDither(true);
    mPaint.setColor(BrushColor);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeWidth(BrushWidth);
    mPaint.setPathEffect(new CornerPathEffect(30) );
    //mEmboss = new EmbossMaskFilter(new float[] { 1, 1, 1 },0.4f, 6, 3.5f);

    //mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.NORMAL);
}

public void onClick(View view){
    switch (view.getId()){
    case R.id.undoBtn:  
        mView.onClickUndo();
    break;

    case R.id.redoBtn:
        mView.onClickRedo();
    break;

    case R.id.saveBtn:
        File myDir=new File("/sdcard/Pictures/Draw");
        myDir.mkdirs();
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date(System.currentTimeMillis())); //***
        String fname = timeStamp + ".png";
        File file = new File (myDir, fname);
        System.out.println(file+"----> file");
        if (file.exists ()) file.delete ();
        saveAsPng(file);
    break;


    }
}

public void saveAsPng (File f)
{
    String fname = f.getAbsolutePath ();

    FileOutputStream fos = null;
    try {
        fos = new FileOutputStream (f);
        mView.mBitmap.compress (CompressFormat.PNG, 100, fos);  
        sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://"+ Environment.getExternalStorageDirectory())));
        Toast.makeText (getApplicationContext(), "Saved " + fname, Toast.LENGTH_LONG).show ();
    } catch (Throwable ex) {
      Toast.makeText (getApplicationContext(), "Error: " + ex.getMessage (), Toast.LENGTH_LONG).show ();
      ex.printStackTrace ();
    }

} // end saveAsPng

} // end Main

---MyView类

public class MyView extends View {

/**
 */
// Constants and variables
    private static final float MINP = 0.25f;
    private static final float MAXP = 0.75f;

    public static Bitmap  mBitmap;
    private Canvas  mCanvas;
    private Path    mPath;
    private Paint   mBitmapPaint;
    private ArrayList<Path> paths = new ArrayList<Path>();
    private ArrayList<Path> undonePaths = new ArrayList<Path>(); 

   // public int backgroundColor;

/**
 */

    public MyView(Context c) 
    {
        super(c);
        /*if (Draw.selectedImagePath == null) {*/
        setFocusable(true);
        setFocusableInTouchMode(true);      
            // Figure out how this works. Seems odd that we set up a canvas and a bitmap. 
            // I don't see how it connects to what shows on screen.    
            mBitmap = Bitmap.createBitmap(Draw4FunMain.WW, Draw4FunMain.WH, Bitmap.Config.ARGB_8888);
            mCanvas = new Canvas(mBitmap);
            mPath = new Path();
            mBitmapPaint = new Paint(Paint.DITHER_FLAG);
            // mCanvas.setBackgroundResource(0xFFFFFFFF);
            if (Draw.imageBackgroundEraser == null) {
                mCanvas.drawColor (Color.WHITE);
            } else {
                mCanvas.drawColor (Color.TRANSPARENT); 
            }
             mCanvas.drawColor(Color.TRANSPARENT);
    }

    public MyView (Context c, int color)
    {
        super(c);
        setFocusable(true);
        setFocusableInTouchMode(true);      
            mBitmap = Bitmap.createBitmap(Draw.WW, Draw.WH, Bitmap.Config.ARGB_8888);
            mCanvas = new Canvas(mBitmap);
            mPath = new Path();
            mBitmapPaint = new Paint(Paint.DITHER_FLAG);
            mCanvas.drawColor (color);

    }

/**
 */
// Methods

/**
 */
@Override protected void onSizeChanged(int w, int h, int oldw, int oldh) 
{
    super.onSizeChanged(w, h, oldw, oldh);
}

/**
 */
@Override protected void onDraw(Canvas canvas) 
{

         // canvas.drawColor(Color.TRANSPARENT);

          canvas.drawBitmap(mBitmap, 0, 0, null);

          for (Path p : paths){
              canvas.drawPath(p, Draw.mPaint);
              //System.out.println("p-->" + p);
             // System.out.println("Draw.mPaint-->" + Draw4FunMain.mPaint);
          }
          canvas.drawPath(mPath, Draw.mPaint);

}

/**
 */
    private float mX, mY;
    private static final float TOUCH_TOLERANCE = 4;

/**
 */
    private void touch_start(float x, float y) {
        mPath.reset(); //-------------------------
        mPath.moveTo(x, y);
        mX = x;
        mY = y;
    }
/**
 */
    private void touch_move(float x, float y) {
        float dx = Math.abs(x - mX);
        float dy = Math.abs(y - mY);
        if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
            mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
            mX = x;
            mY = y;
        }
    }
/**
 */
    private void touch_up() {
        mPath.lineTo(mX, mY);
        // commit the path to our offscreen
        mCanvas.drawPath(mPath, Draw.mPaint);
        // kill this so we don't double draw
        mPath.reset();

        paths.add(mPath);
        mPath = new Path();
        System.out.println("path-->" + paths);  
        System.out.println("size-->" + paths.size());
    }

/**
 */
    public void onClickUndo () { 
        if (paths.size()>0) 
        { 
           undonePaths.add(paths.remove(paths.size()-1));
           invalidate();
         }
        else
        {

        }
         //toast the user 
    }

    public void onClickRedo (){
        if (undonePaths.size()>0) 
       { 
           paths.add(undonePaths.remove(undonePaths.size()-1)); 
           invalidate();
       } 
       else 
       {

       }
    }

@Override public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX();
        float y = event.getY();

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                touch_start(x, y);
                invalidate();
                break;
            case MotionEvent.ACTION_MOVE:
                touch_move(x, y);
                invalidate();
                break;
            case MotionEvent.ACTION_UP:
                touch_up();
                invalidate();
                break;
        }
        return true;
    }

} // end MyView

---

logCat在代码的第246行指出一个NullPointerException。我假设是这样的：

public void onClick(View view){
    switch (view.getId()){
    case R.id.undoBtn:  
        mView.onClickUndo();
    break;

    case R.id.redoBtn:
        mView.onClickRedo();
    break;

---

问题是，您没有初始化

mView

。在

onCreate

中，您可以初始化一个局部变量

myView

。将该实例分配给

mView

应该可以解决您的问题。

您的日志猫在代码的第246行指出一个NullPointerException。我假设是这样的：

public void onClick(View view){
    switch (view.getId()){
    case R.id.undoBtn:  
        mView.onClickUndo();
    break;

    case R.id.redoBtn:
        mView.onClickRedo();
    break;

---

问题是，您没有初始化

mView

。在

onCreate

中，您可以初始化一个局部变量

myView

。将该实例分配给

mView

应该可以解决您的问题。

是。我也认为保罗·扬是正确的。下线

final MyView myView = new MyView(this);

java中的at onCreate方法应使用as just进行更正

myView = new MyView(this);

---

对。我也认为保罗·扬是正确的。下线

final MyView myView = new MyView(this);

java中的at onCreate方法应使用as just进行更正

myView = new MyView(this);

---

你们班的第246行是什么？好的。它崩溃了，因为mView为null。在onCreate（）方法中初始化它。类Draw4FunMain的第246行是什么？好的。它崩溃了，因为mView为null。在onCreate（）方法中初始化它。我将假设。？我们能为别人的代码做出自己的假设吗@SahilMahajanMj：我认为在这种情况下，我们可以，是的。我将假设。？我们能为别人的代码做出自己的假设吗@SahilMahajanMj：我认为在这种情况下，我们可以，是的。