我已经使用了相同的代码块，已经在接受的答案，但它不会像在android 9一样工作，所以更新措施根据这一点

v.measure(MeasureSpec.makeMeasureSpec(parentView.getWidth(), MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(parentView.getWidth(), MeasureSpec.AT_MOST));

约束的工作方式在android 9中有所不同。

另一种选择是使用以下缩放因子的缩放动画进行扩展:

ScaleAnimation anim = new ScaleAnimation(1, 1, 0, 1);

至于坍塌:

ScaleAnimation anim = new ScaleAnimation(1, 1, 1, 0);

这是一个合适的工作解决方案，我已经测试过了:

例如：

private void expand(View v) {
    v.setVisibility(View.VISIBLE);

    v.measure(View.MeasureSpec.makeMeasureSpec(PARENT_VIEW.getWidth(), View.MeasureSpec.EXACTLY),
            View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));

    final int targetHeight = v.getMeasuredHeight();

    mAnimator = slideAnimator(0, targetHeight);
    mAnimator.setDuration(800);
    mAnimator.start();
}

崩溃:

private void collapse(View v) {
    int finalHeight = v.getHeight();

    mAnimator = slideAnimator(finalHeight, 0);

    mAnimator.addListener(new Animator.AnimatorListener() {
        @Override
        public void onAnimationStart(Animator animator) {

        }

        @Override
        public void onAnimationEnd(Animator animator) {
            //Height=0, but it set visibility to GONE
            llDescp.setVisibility(View.GONE);
        }

        @Override
        public void onAnimationCancel(Animator animator) {

        }

        @Override
        public void onAnimationRepeat(Animator animator) {

        }
    });
    mAnimator.start();
}

动画师的值:

private ValueAnimator slideAnimator(int start, int end) {
    ValueAnimator mAnimator = ValueAnimator.ofInt(start, end);

    mAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator valueAnimator) {
            //Update Height
            int value = (Integer) valueAnimator.getAnimatedValue();
            ViewGroup.LayoutParams layoutParams = llDescp.getLayoutParams();
            layoutParams.height = value;
            v.setLayoutParams(layoutParams);
        }
    });
    return mAnimator;
}

视图v是要被动画的视图，PARENT_VIEW是包含该视图的容器视图。

这是一个片段，我用来调整一个视图(线性布局)的宽度与动画。

代码应该根据目标大小进行扩展或收缩。如果你想要一个fill_parent宽度，你必须在将标志设置为true时将父类. getmeasuredwidth作为目标宽度。

希望它能帮助到你们中的一些人。

public class WidthResizeAnimation extends Animation {
int targetWidth;
int originaltWidth;
View view;
boolean expand;
int newWidth = 0;
boolean fillParent;

public WidthResizeAnimation(View view, int targetWidth, boolean fillParent) {
    this.view = view;
    this.originaltWidth = this.view.getMeasuredWidth();
    this.targetWidth = targetWidth;
    newWidth = originaltWidth;
    if (originaltWidth > targetWidth) {
        expand = false;
    } else {
        expand = true;
    }
    this.fillParent = fillParent;
}

@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
    if (expand && newWidth < targetWidth) {
        newWidth = (int) (newWidth + (targetWidth - newWidth) * interpolatedTime);
    }

    if (!expand && newWidth > targetWidth) {
        newWidth = (int) (newWidth - (newWidth - targetWidth) * interpolatedTime);
    }
    if (fillParent && interpolatedTime == 1.0) {
        view.getLayoutParams().width = -1;

    } else {
        view.getLayoutParams().width = newWidth;
    }
    view.requestLayout();
}

@Override
public void initialize(int width, int height, int parentWidth, int parentHeight) {
    super.initialize(width, height, parentWidth, parentHeight);
}

@Override
public boolean willChangeBounds() {
    return true;
}

}

你可以稍微改变一下使用ViewPropertyAnimator。若要折叠，请将视图缩放到1像素的高度，然后隐藏它。展开，显示它，然后展开到它的高度。

private void collapse(final View view) {
    view.setPivotY(0);
    view.animate().scaleY(1/view.getHeight()).setDuration(1000).withEndAction(new Runnable() {
        @Override public void run() {
            view.setVisibility(GONE);
        }
    });
}

private void expand(View view, int height) {
    float scaleFactor = height / view.getHeight();

    view.setVisibility(VISIBLE);
    view.setPivotY(0);
    view.animate().scaleY(scaleFactor).setDuration(1000);
}

枢轴告诉视图从哪里开始缩放，默认是在中间。持续时间是可选的(默认= 1000)。你也可以设置插值器来使用，比如.setInterpolator(new accelerateeraderateinterpolator ())

利用Kotlin扩展函数这是测试和最短的答案

在任何视图上调用animateVisibility(expand/collapse)即可。

fun View.animateVisibility(setVisible: Boolean) {
    if (setVisible) expand(this) else collapse(this)
}

private fun expand(view: View) {
    view.measure(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT)
    val initialHeight = 0
    val targetHeight = view.measuredHeight

    // Older versions of Android (pre API 21) cancel animations for views with a height of 0.
    //v.getLayoutParams().height = 1;
    view.layoutParams.height = 0
    view.visibility = View.VISIBLE

    animateView(view, initialHeight, targetHeight)
}

private fun collapse(view: View) {
    val initialHeight = view.measuredHeight
    val targetHeight = 0

    animateView(view, initialHeight, targetHeight)
}

private fun animateView(v: View, initialHeight: Int, targetHeight: Int) {
    val valueAnimator = ValueAnimator.ofInt(initialHeight, targetHeight)
    valueAnimator.addUpdateListener { animation ->
        v.layoutParams.height = animation.animatedValue as Int
        v.requestLayout()
    }
    valueAnimator.addListener(object : Animator.AnimatorListener {
        override fun onAnimationEnd(animation: Animator) {
            v.layoutParams.height = targetHeight
        }

        override fun onAnimationStart(animation: Animator) {}
        override fun onAnimationCancel(animation: Animator) {}
        override fun onAnimationRepeat(animation: Animator) {}
    })
    valueAnimator.duration = 300
    valueAnimator.interpolator = DecelerateInterpolator()
    valueAnimator.start()
}