UiStateController.java

package com.rajesh.retrofit2example;

import android.os.Bundle;
import android.support.annotation.AnimRes;
import android.support.annotation.IntDef;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;


/**
 * Author: Rajesh Batth
 * Date: 27-Sep-2015.
 */
public class UiStateController {

  private static final String STATE_CURRENT_UI_STATE = "STATE_CURRENT_UI_STATE";
  private static final String STATE_APPEAR_ANIMATION_RES_ID = "STATE_APPEAR_ANIMATION_RES_ID";
  private static final String STATE_DISAPPEAR_ANIMATION_RES_ID = "STATE_DISAPPEAR_ANIMATION_RES_ID";

  public static final int UI_STATE_LOADING = 0;
  public static final int UI_STATE_ERROR = 1;
  public static final int UI_STATE_EMPTY = 2;
  public static final int UI_STATE_CONTENT = 3;

  @IntDef({ UI_STATE_CONTENT, UI_STATE_EMPTY, UI_STATE_ERROR, UI_STATE_LOADING })
  public @interface UiState {
  }

  @Nullable
  private final View loadingUiView, errorUiView, emptyUiView, contentUiView;

  @Nullable
  @AnimRes
  private Integer appearAnimationResId, disappearAnimationResId;

  @UiState
  public int getCurrentUiState() {
    return currentUiState;
  }


  @UiState
  private int currentUiState = UI_STATE_CONTENT;

  private UiStateController(@Nullable View loadingUiView, @Nullable View errorUiView,
      @Nullable View emptyUiView, @Nullable View contentUiView,
      @Nullable @AnimRes Integer appearAnimationResId,
      @Nullable @AnimRes Integer disappearAnimationResId) {
    this.loadingUiView = loadingUiView;
    this.errorUiView = errorUiView;
    this.emptyUiView = emptyUiView;
    this.contentUiView = contentUiView;
    this.appearAnimationResId = appearAnimationResId;
    this.disappearAnimationResId = disappearAnimationResId;
  }

  private void makeViewAppear(@NonNull final View view) {
    if (view.getVisibility() == View.VISIBLE) {
      return;
    }

    if (appearAnimationResId != null) {
      final Animation animation =
          AnimationUtils.loadAnimation(view.getContext(), appearAnimationResId);
      animation.setAnimationListener(new Animation.AnimationListener() {
        @Override
        public void onAnimationStart(Animation animation) {
          view.setVisibility(View.VISIBLE);
        }

        @Override
        public void onAnimationEnd(Animation animation) {

        }

        @Override
        public void onAnimationRepeat(Animation animation) {

        }
      });
      view.startAnimation(animation);
    } else {
      view.setVisibility(View.VISIBLE);
    }
  }

  private void makeViewDisappear(@NonNull final View view) {
    if (view.getVisibility() == View.GONE) {
      return;
    }

    if (disappearAnimationResId != null) {
      final Animation animation =
          AnimationUtils.loadAnimation(view.getContext(), disappearAnimationResId);
      animation.setAnimationListener(new Animation.AnimationListener() {
        @Override
        public void onAnimationStart(Animation animation) {

        }

        @Override
        public void onAnimationEnd(Animation animation) {
          view.setVisibility(View.GONE);
        }

        @Override
        public void onAnimationRepeat(Animation animation) {

        }
      });
      view.startAnimation(animation);
    } else {
      view.setVisibility(View.GONE);
    }
  }

  private void makeViewsDisappear(@NonNull View... views) {
    for (View view : views) {
      if (view != null) {
        makeViewDisappear(view);
      }
    }
  }

  public void setUiStateLoading() {
    if (loadingUiView == null) {
      throw new IllegalStateException("Please set loadingUiView");
    }

    makeViewAppear(loadingUiView);
    makeViewsDisappear(errorUiView, emptyUiView, contentUiView);

    currentUiState = UI_STATE_LOADING;
  }

  public void setUiStateError() {
    if (errorUiView == null) {
      throw new IllegalStateException("Please set errorUiView");
    }

    makeViewAppear(errorUiView);
    makeViewsDisappear(loadingUiView, emptyUiView, contentUiView);

    currentUiState = UI_STATE_ERROR;
  }

  public void setUiStateEmpty() {
    if (emptyUiView == null) {
      throw new IllegalStateException("Please set emptyUiView");
    }

    makeViewAppear(emptyUiView);
    makeViewsDisappear(loadingUiView, errorUiView, contentUiView);

    currentUiState = UI_STATE_EMPTY;
  }

  public void setUiStateContent() {
    if (contentUiView == null) {
      throw new IllegalStateException("Please set contentUiView");
    }

    makeViewAppear(contentUiView);
    makeViewsDisappear(loadingUiView, errorUiView, emptyUiView);

    currentUiState = UI_STATE_CONTENT;
  }

  public void saveState(@NonNull Bundle outState) {
    outState.putInt(STATE_CURRENT_UI_STATE, currentUiState);

    if (appearAnimationResId != null) {
      outState.putInt(STATE_APPEAR_ANIMATION_RES_ID, appearAnimationResId);
    }

    if (disappearAnimationResId != null) {
      outState.putInt(STATE_DISAPPEAR_ANIMATION_RES_ID, disappearAnimationResId);
    }
  }

  public void restoreState(@NonNull Bundle savedInstanceState) {
    currentUiState = savedInstanceState.getInt(STATE_CURRENT_UI_STATE, UI_STATE_LOADING);

    // preventing animations on restore state
    appearAnimationResId = null;
    disappearAnimationResId = null;

    // setting state without animations
    if (currentUiState == UI_STATE_LOADING) {
      setUiStateLoading();
    } else if (currentUiState == UI_STATE_ERROR) {
      setUiStateError();
    } else if (currentUiState == UI_STATE_CONTENT) {
      setUiStateContent();
    }

    // check required to allow null value
    if (savedInstanceState.containsKey(STATE_APPEAR_ANIMATION_RES_ID)) {
      appearAnimationResId = savedInstanceState.getInt(STATE_APPEAR_ANIMATION_RES_ID);
    }

    // check required to allow null value
    if (savedInstanceState.containsKey(STATE_DISAPPEAR_ANIMATION_RES_ID)) {
      disappearAnimationResId = savedInstanceState.getInt(STATE_DISAPPEAR_ANIMATION_RES_ID);
    }
  }

  public static class Builder {

    @Nullable
    private View loadingUiView, errorUiView, emptyUiView, contentUiView;
    @Nullable
    private Integer appearAnimationResId;
    @Nullable
    private Integer disappearAnimationResId;

    @NonNull
    public Builder withLoadingUi(@NonNull View loadingUiView) {
      this.loadingUiView = loadingUiView;
      return this;
    }

    @NonNull
    public Builder withErrorUi(@NonNull View errorUiView) {
      this.errorUiView = errorUiView;
      return this;
    }

    @NonNull
    public Builder withEmptyUi(@NonNull View emptyUi) {
      this.emptyUiView = emptyUi;
      return this;
    }

    @NonNull
    public Builder withContentUi(@NonNull View contentUiView) {
      this.contentUiView = contentUiView;
      return this;
    }

    @NonNull
    public Builder withAppearAnimation(@Nullable @AnimRes Integer appearAnimation) {
      appearAnimationResId = appearAnimation;
      return this;
    }

    @NonNull
    public Builder withDisappearAnimation(@Nullable @AnimRes Integer disappearAnimation) {
      disappearAnimationResId = disappearAnimation;
      return this;
    }

    @NonNull
    public UiStateController build() {
      return new UiStateController(loadingUiView, errorUiView, emptyUiView, contentUiView,
          appearAnimationResId, disappearAnimationResId);
    }
  }
}