【Android】getLeft（），getRight（）值为0，应在何时正确获取他们的值

本文主要是介绍【Android】getLeft（），getRight（）值为0，应在何时正确获取他们的值，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

1.问题所在

.getLeft() .getRight() .getTop() .getBottom(),是获取当前view相对于父view的相应距离，但是获取的时机错误的话，view的四个值就获取不到。先来看个例子

我一共在六个地方获取了view的getLeft和getRight

1）在onCreate中获取

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_testanim);
    initPop();
    mHandlerPlus = new HandlerPlus(this);
    mImg = (ImageView) findViewById(R.id.mImg_pop);
    Log.e(TAG, "onCreate: &&&&&&&&&&&&&&");
    Log.e(TAG, "mImg.getLeft()--->"+mImg.getLeft());
    Log.e(TAG, "mImg.getRight()--->"+mImg.getRight());
}

2）在onAttachToWindow中获取

@Override
public void onAttachedToWindow() {super.onAttachedToWindow();
    Log.e(TAG, "onAttachedToWindow: *************************");
    Log.e(TAG, "mImg.getLeft()--->"+mImg.getLeft());
    Log.e(TAG, "mImg.getRight()--->"+mImg.getRight());
}

3）在布局监听中获取

View.OnAttachStateChangeListener mOnAttachStateChangeListener = new View.OnAttachStateChangeListener() {@Override
    public void onViewAttachedToWindow(View v) {parentHeight = getWindowWH(1);
        parentWidth = getWindowWH(0);
        viewHeight = dealViewWH(img_one, 1);
        viewWidth = dealViewWH(img_one, 0);
        Log.e(TAG, "onViewAttachedToWindow: =====================");
        Log.e(TAG, "mImg.getLeft()--->"+mImg.getLeft());
        Log.e(TAG, "mImg.getRight()--->"+mImg.getRight());

    }@Override
    public void onViewDetachedFromWindow(View v) {}
};

4)在视图树的监听中获取

mImg.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {@Override
    public void onGlobalLayout() {Log.e(TAG, "onGlobalLayout:++++++++++++++++++++ ");
        Log.e(TAG, "mImg.getLeft()--->"+mImg.getLeft());
        Log.e(TAG, "mImg.getRight()--->"+mImg.getRight());
    }
});

5)在view的post中异步获取

mImg.post(new Runnable() {@Override
    public void run() {Log.e(TAG, "run: $$$$$$$$$$$$$$$$");
        Log.e(TAG, "mImg.getLeft()--->"+mImg.getLeft());
        Log.e(TAG, "mImg.getRight()--->"+mImg.getRight());
    }
});

6)在window焦点改变的时候获取

@Override
public void onWindowFocusChanged(boolean hasFocus) {super.onWindowFocusChanged(hasFocus);
    if (hasFocus){Log.e(TAG, "onWindowFocusChanged: %%%%%%%%%%%%%%%%%");
        Log.e(TAG, "mImg.getLeft()--->"+mImg.getLeft());
        Log.e(TAG, "mImg.getRight()--->"+mImg.getRight());
    }
}