小编Mis*_*sha的帖子

我在我的应用程序中有这个自定义相机活动,它运行得很好,但是当我在相机活动中按下主页按钮,然后返回应用程序时,它崩溃了,并且logcat说有一个空指针异常在表面视图创建.在onResume上调用此设置方法:

    public void setup()
    {

    preview = new CameraPreview(this);
    ((FrameLayout) findViewById(R.id.camera_preview)).addView(preview);
    head=(ImageView)findViewById(R.id.head);
        head.setX((float)(Shared.screenWidth/5*1.8));
        head.setY((float)(Shared.screenHeight*0.03));
        LayoutParams params = (LayoutParams) head.getLayoutParams();
        params.width = (int)((Shared.screenWidth/5*3.2)-(head.getX()));
        params.height=(int)((Shared.screenHeight/3.8)-(head.getY()));
        head.setLayoutParams(params);
    body=(ImageView)findViewById(R.id.body);
        body.setX((float)(Shared.screenWidth/7));
        body.setY((float)(Shared.screenHeight/3.8));
        LayoutParams params2 = (LayoutParams) body.getLayoutParams();
        params2.width = (int)((Shared.screenWidth/7*6)-(body.getX()));
        params2.height=(int)((Shared.screenHeight)-(body.getY()));
        body.setLayoutParams(params2);
    go=(Button)findViewById(R.id.go);
    again=(Button)findViewById(R.id.again);
    stop=(ImageButton)findViewById(R.id.stop);
    stop.setOnClickListener( new OnClickListener() {
        public void onClick(View v) {
            Intent i =new Intent(CamActivity.this,Main.class);
            i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); 
            startActivity(i);


        }
    });
    btn = (ImageButton) findViewById(R.id.takePic);
    btn.setOnClickListener( new OnClickListener() {
        public void onClick(View v) {
            preview.camera.takePicture(shutterCallback, rawCallback, jpegCallback);
            btn.setVisibility(View.INVISIBLE);
            btn.setEnabled(false);
            go.setVisibility(View.VISIBLE);
            go.setEnabled(true);
            head.setVisibility(View.INVISIBLE);
            body.setVisibility(View.INVISIBLE);
            go.setOnClickListener( …