Android expand/collapse RelativeLayout

Question

I've tried various solutions from this topic (see. Android: Expand/collapse animation ) and none of them really worked for me. I'm sure that the most voted ones are good and the reason that it won't work is that I don't understand something. Please tell me what i'm doing wrong. Thank you in advance :)

EDIT: The main point of my problem is, that when I click on the element 'relativeZaplon' it expands very well, yet when I want to collapse it, it does not correspond.

MainActivity

 public class MainActivity extends AppCompatActivity {

    private boolean isVisible = false;
    private RelativeLayout mRelativeZaplon;
    private RelativeLayout mRelativeToSlide;
    private ExpandOrCollapse mAnimationManager;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mAnimationManager = new ExpandOrCollapse();
        mRelativeZaplon = (RelativeLayout) findViewById(R.id.relativeZaplon);
        mRelativeToSlide = (RelativeLayout) findViewById(R.id.relativevToSlide);
        mRelativeZaplon.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (isVisible) {
                    mAnimationManager.collapse(mRelativeToSlide, 1000, 200);
                    isVisible = false;
                } else if (!isVisible){
                    mAnimationManager.expand(mRelativeToSlide, 1000, 200);
                    isVisible = true;
                }
            }
        });
    }
}

Expand/Collapse Class

    public class ExpandOrCollapse {

    public static void expand(final View v, int duration, int targetHeight) {
        int prevHeight  = v.getHeight();
        v.setVisibility(View.VISIBLE);
        ValueAnimator valueAnimator = ValueAnimator.ofInt(prevHeight, targetHeight);
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                v.getLayoutParams().height = (int) animation.getAnimatedValue();
                v.requestLayout();
            }
        });
        valueAnimator.setInterpolator(new DecelerateInterpolator());
        valueAnimator.setDuration(duration);
        valueAnimator.start();
    }

    public static void collapse(final View v, int duration, int targetHeight) {
        int prevHeight  = v.getHeight();
        ValueAnimator valueAnimator = ValueAnimator.ofInt(prevHeight, targetHeight);
        valueAnimator.setInterpolator(new DecelerateInterpolator());
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                v.getLayoutParams().height = (int) animation.getAnimatedValue();
                v.requestLayout();
            }
        });
        valueAnimator.setInterpolator(new DecelerateInterpolator());
        valueAnimator.setDuration(duration);
        valueAnimator.start();
    }
}

XML

 <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <RelativeLayout
        android:background="@color/colorPrimaryDark"
        android:id="@+id/relativevToSlide"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:visibility="gone">
    </RelativeLayout>
    <RelativeLayout
        android:id="@+id/relativeZaplon"
        android:background="@color/colorAccent"
        android:layout_width="match_parent"
        android:layout_height="20dp"
        android:layout_below="@+id/relativevToSlide"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true">
    </RelativeLayout>
</LinearLayout>

Answer 1

This is my version of the method, you don´t have to set any height, it will expand or collapse any view depending on its visibility.

public static void expand(final View v, int duration) {
    final boolean expand = v.getVisibility()!=View.VISIBLE;

    int prevHeight  = v.getHeight();
    int height = 0;
    if (expand) {
        int measureSpecParams = View.MeasureSpec.getSize(View.MeasureSpec.UNSPECIFIED);
        v.measure(measureSpecParams, measureSpecParams);
        height = v.getMeasuredHeight();
    }

    ValueAnimator valueAnimator = ValueAnimator.ofInt(prevHeight, height);
    valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            v.getLayoutParams().height = (int) animation.getAnimatedValue();
            v.requestLayout();
        }
    });

    valueAnimator.addListener(new Animator.AnimatorListener() {
        @Override
        public void onAnimationStart(Animator animation) {
            if (expand){
                v.setVisibility(View.VISIBLE);
            }
        }

        @Override
        public void onAnimationEnd(Animator animation) {
            if (!expand){
                v.setVisibility(View.INVISIBLE);
            }
        }

        @Override
        public void onAnimationCancel(Animator animation) {

        }

        @Override
        public void onAnimationRepeat(Animator animation) {

        }
    });
    valueAnimator.setInterpolator(new DecelerateInterpolator());
    valueAnimator.setDuration(duration);
    valueAnimator.start();
}

Just call the method like this:

expand(YOURVIEWID,500);