Android Open Source - Android-Infinite-Scroll-Listview Infinite Scroll List View

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License

The source code is released under:

Apache License

Java Source Code

/**
 */*w ww.  j  a v  a 2s .  c o m*/
 * Copyright 2013 Wei Xiao
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 */

package ca.weixiao.widget;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.ListAdapter;
import android.widget.ListView;

/**
 * A ListView with upward/downward infinite scrolling capability, with a customizable view
 * to be displayed at the top/bottom of the list as the loading indicator
 */
public class InfiniteScrollListView extends ListView implements InfiniteScrollListPageListener {

  public static final String TAG = InfiniteScrollListView.class.getSimpleName();
  // Two conditions allowing loading to happen: either the list view scrolls to the top or bottom
  public static enum LoadingMode {SCROLL_TO_TOP, SCROLL_TO_BOTTOM};
  // Decides where the ending position: either scrolls up to the start of the list, scrolls down to the 
  // end of the list or where remains where it was
  public static enum StopPosition {START_OF_LIST, END_OF_LIST, REMAIN_UNCHANGED};

  private View loadingView;
  private LoadingMode loadingMode = LoadingMode.SCROLL_TO_BOTTOM; 
  private StopPosition stopPosition = StopPosition.REMAIN_UNCHANGED;

  // A flag to prevent loading header or footer more than once
  private boolean loadingViewVisible = false;

    public InfiniteScrollListView(Context context) {
        super(context);
    }

    public InfiniteScrollListView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public InfiniteScrollListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }
    
    public void setLoadingView(View loadingView) {
    this.loadingView = loadingView;
  }

    public void setLoadingMode(LoadingMode loadingMode) {
      this.loadingMode = loadingMode;
    }
    
    public void setStopPosition(StopPosition stopPosition) {
    this.stopPosition = stopPosition;
  }

    private void addLoadingView(ListView listView, View loadingView) {
      if (listView == null || loadingView == null) {
        return;
      }
      // Avoid overlapping the header or footer
      if (!loadingViewVisible) {
      if (loadingMode == LoadingMode.SCROLL_TO_TOP) {
        // Add loading view to list view header when scroll up to load
        listView.addHeaderView(loadingView);
      } else {
        // Add loading view to list view footer when scroll down to load
        listView.addFooterView(loadingView);
      }
      loadingViewVisible = true;
      }
    }

    private void removeLoadingView(ListView listView, View loadingView) {
      if (listView == null || loadingView == null) {
        return;
      }
      // Remove header or footer depending on the loading mode
      if (loadingViewVisible) {
        if (loadingMode == LoadingMode.SCROLL_TO_TOP) {
        listView.removeHeaderView(loadingView);
      } else {
        listView.removeFooterView(loadingView);
      }
        loadingViewVisible = false;
      }
    }

    @Override
    public void setAdapter(ListAdapter adapter) {
      // Force the list view to accept its own type of adapter
      if (!(adapter instanceof InfiniteScrollListAdapter)) {
        throw new IllegalArgumentException(InfiniteScrollListAdapter.class.getSimpleName() + " expected");
      }
      // Pass information to adaptor
      InfiniteScrollListAdapter infiniteListAdapter = (InfiniteScrollListAdapter) adapter;
      infiniteListAdapter.setLoadingMode(loadingMode);
      infiniteListAdapter.setStopPosition(stopPosition);
      infiniteListAdapter.setInfiniteListPageListener(this);
    this.setOnScrollListener(infiniteListAdapter);
    // Workaround to keep spaces for header and footer
    View dummy = new View(getContext());
    addLoadingView(InfiniteScrollListView.super, dummy);
      super.setAdapter(adapter);
      removeLoadingView(InfiniteScrollListView.super, dummy);
    }

  @Override
  public void endOfList() {
    // Remove loading view when there is no more to load
    removeLoadingView(this, loadingView);
  }

  @Override
  public void hasMore() {
    // Display loading view when there might be more to load
    addLoadingView(InfiniteScrollListView.this, loadingView);
  }

}

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