Android ContentLayout. The utility class to switch showing content/loading/error/empty efficient way

attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <declare-styleable name="ContentLayout">
    <attr name="content_layout"
        format="reference"/>
    <attr name="error_layout"
        format="reference"/>
    <attr name="empty_layout"
        format="reference"/>
    <attr name="loading_layout"
        format="reference"/>
  </declare-styleable>
</resources>

ContentLayout.java

/**
 * Umbala
 *
 * Created by Giang Nguyen on 9/26/15.
 * Copyright (c) 2015 Umbala. All rights reserved.
 */

package co.umbala.umbala.ui.widget;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.content.Context;
import android.content.res.TypedArray;
import android.support.annotation.LayoutRes;
import android.support.v7.internal.widget.ViewStubCompat;
import android.util.AttributeSet;
import android.view.View;
import android.widget.FrameLayout;
import co.umbala.umbala.R;

public class ContentLayout extends FrameLayout {
  private static final int DURATION = 200;
  private View vContent;
  private View vLoading;
  private View vError;
  private View vEmpty;
  private View showingView;
  private ViewStubCompat vsError;
  private ViewStubCompat vsEmpty;
  private ViewStubCompat vsLoading;
  private ViewStubCompat vsContent;

  public ContentLayout(Context context) {
    this(context, null, 0);
  }

  public ContentLayout(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public ContentLayout(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    final TypedArray a = context.getTheme()
        .obtainStyledAttributes(attrs, R.styleable.ContentLayout, defStyleAttr, 0);
    try {
      int layoutId;
      layoutId = a.getResourceId(R.styleable.ContentLayout_content_layout, 0);
      if (layoutId != 0) {
        vsContent = new ViewStubCompat(context, null);
        vsContent.setLayoutResource(layoutId);
        addView(vsContent);
      }
      layoutId = a.getResourceId(R.styleable.ContentLayout_error_layout, 0);
      if (layoutId != 0) {
        setErrorLayout(layoutId);
      }
      layoutId = a.getResourceId(R.styleable.ContentLayout_loading_layout, 0);
      if (layoutId != 0) {
        setLoadingLayout(layoutId);
      }
      layoutId = a.getResourceId(R.styleable.ContentLayout_empty_layout, 0);
      if (layoutId != 0) {
        setEmptyLayout(layoutId);
      }
    } finally {
      a.recycle();
    }
  }

  private void setLoadingLayout(int layoutId) {
    if (vsLoading != null) {
      // Remove the old View
      removeView(vsLoading);
    }
    vsLoading = new ViewStubCompat(getContext(), null);
    vsLoading.setLayoutResource(layoutId);
    addView(vsLoading);
  }

  public void setErrorLayout(@LayoutRes int layoutId) {
    if (vsError != null) {
      removeView(vsError);
    }
    vsError = new ViewStubCompat(getContext(), null);
    vsError.setLayoutResource(layoutId);
    addView(vsError);
  }

  public void setEmptyLayout(@LayoutRes int layoutId) {
    if (vsEmpty != null) {
      removeView(vsEmpty);
    }
    vsEmpty = new ViewStubCompat(getContext(), null);
    vsEmpty.setLayoutResource(layoutId);
    addView(vsEmpty);
  }

  public View getContentView() {
    if (vContent == null) {
      vContent = inflateEmptyView(vsContent);
    }
    return vContent;
  }

  public View getErrorView() {
    if (vError == null) {
      vError = inflateEmptyView(vsError);
    }
    return vError;
  }

  public void showContent() {
    if (vContent == null) {
      vContent = inflateEmptyView(vsContent);
    }
    if (showingView == vContent) {
      return;
    }
    crossFade(vContent, showingView);
    showingView = vContent;
  }

  public void showError() {
    if (vError == null) {
      vError = inflateEmptyView(vsError);
    }
    if (showingView == vError) {
      return;
    }
    crossFade(vError, showingView);
    showingView = vError;
  }

  public void showLoading() {
    if (vLoading == null) {
      vLoading = inflateEmptyView(vsLoading);
    }
    if (showingView == vLoading) {
      return;
    }
    crossFade(vLoading, showingView);
    showingView = vLoading;
  }

  public void showEmpty() {
    if (vEmpty == null) {
      vEmpty = inflateEmptyView(vsEmpty);
    }
    if (showingView == vEmpty) {
      return;
    }
    // Show empty
    crossFade(vEmpty, showingView);
    showingView = vEmpty;
  }

  private View inflateEmptyView(ViewStubCompat viewStub) {
    if (viewStub == null) {
      throw new NullPointerException("Must specify the layout in xml");
    }
    return viewStub.inflate();
  }

  private void crossFade(View showView, final View hideView) {
    if (showView == null && hideView == null) {
      return;
    }
    if (showView == null) {
      hide(hideView);
    } else if (hideView == null) {
      show(showView);
    } else {
      final Animator hideAnimator = hideAnimator(hideView);
      final Animator showAnimator = showAnimator(showView);
      final AnimatorSet animatorSet = new AnimatorSet().setDuration(200);
      animatorSet.addListener(new AnimatorListenerAdapter() {
        @Override public void onAnimationEnd(Animator animation) {
          super.onAnimationEnd(animation);
          hideView.setVisibility(GONE);
        }
      });
      showView.setVisibility(VISIBLE);
      animatorSet.playTogether(showAnimator, hideAnimator);
      animatorSet.start();
    }
  }

  private void hide(final View view) {
    final Animator animator = hideAnimator(view);
    animator.setDuration(DURATION).addListener(new AnimatorListenerAdapter() {
      @Override public void onAnimationEnd(Animator animation) {
        super.onAnimationEnd(animation);
        // Clear side-effect by this callback
        animator.removeListener(this);
        view.setVisibility(GONE);
      }
    });
    animator.start();
  }

  private void show(final View view) {
    view.setVisibility(VISIBLE);
    showAnimator(view).setDuration(DURATION).start();
  }

  private Animator hideAnimator(View target) {
    return ObjectAnimator.ofFloat(target, "alpha", 0f);
  }

  private Animator showAnimator(View target) {
    return ObjectAnimator.ofFloat(target, "alpha", 1f);
  }
}