Android recyclerview实现拖拽排序和侧滑删除

recyclerview现在基本已经替代listview了，recyclerview也越来越好用了  当我们有实现条目的拖拽排序和侧滑删除时  可以直接时候recyclerview提供的api就可以直接实现了
先贴上主要代码

private void initveiw() {
  arraylist<string> items = new arraylist<>(arrays.aslist("itme1", "item2", "itme3", "item4", "item5", "item6", "item7", "item8", "itme9", "item10", "itme11", "item12", "item13", "item14", "item15", "item16"));
  recyclerview.setlayoutmanager(new linearlayoutmanager(this,linearlayoutmanager.vertical,false));
  simpleadapter adapter = new simpleadapter(items);
  recyclerview.setadapter(adapter);
  itemtouchhelper helper = new itemtouchhelper(new myitemtouchcallback(adapter));
  helper.attachtorecyclerview(recyclerview);
}

public class myitemtouchcallback extends itemtouchhelper.callback{

  private simpleadapter adapter;

  public myitemtouchcallback(simpleadapter adapter) {
    this.adapter = adapter;
  }

  @override
  public int getmovementflags(recyclerview recyclerview, recyclerview.viewholder viewholder) {
    int dragflag;
    int swipeflag;
    recyclerview.layoutmanager manager = recyclerview.getlayoutmanager();
    if (manager instanceof gridlayoutmanager){
      dragflag = itemtouchhelper.down | itemtouchhelper.up | itemtouchhelper.left | itemtouchhelper.right;
      swipeflag = 0;
    }else{
      dragflag = itemtouchhelper.down | itemtouchhelper.up;
      swipeflag = itemtouchhelper.end | itemtouchhelper.start;
    }

    return makemovementflags(dragflag,swipeflag);
  }

  @override
  public boolean onmove(recyclerview recyclerview, recyclerview.viewholder viewholder, recyclerview.viewholder target) {
    int fromposition = viewholder.getadapterposition();
    int toposition = target.getadapterposition();
    if (fromposition < toposition ){
      for (int i = fromposition ;i<toposition ;i++){
        collections.swap(adapter.getdatalist(),i,i+1);
      }
    }else{
      for (int i= fromposition; i>toposition; i--){
        collections.swap(adapter.getdatalist(),i ,i-1);
      }
    }
    recyclerview.getadapter().notifyitemmoved(fromposition,toposition);
    return true;
  }

  @override
  public void onswiped(recyclerview.viewholder viewholder, int direction) {
    int position = viewholder.getadapterposition();
    if (direction == itemtouchhelper.end | direction==itemtouchhelper.start){
      adapter.getdatalist().remove(position);
      adapter.notifyitemremoved(position);
    }
  }

  @override
  public void onselectedchanged(recyclerview.viewholder viewholder, int actionstate) {
    super.onselectedchanged(viewholder, actionstate);
    if (actionstate==itemtouchhelper.action_state_drag){
      viewholder.itemview.setbackgroundcolor(color.blue);
    }

  }

  @override
  public void clearview(recyclerview recyclerview, recyclerview.viewholder viewholder) {
    super.clearview(recyclerview, viewholder);
    viewholder.itemview.setbackgroundcolor(0);
  }
}

步骤：

创建 itemtouchhelper 对象时候，需要我们传入一个实现了 itemtouchhelper.callback 接口的对象。而排序和删除的逻辑都封装在了这个 itemtouchhelper.callback 的对象里面了。

private void initveiw() {
  arraylist<string> items = new arraylist<>(arrays.aslist("itme1", "item2", "itme3", "item4", "item5", "item6", "item7", "item8", "itme9", "item10", "itme11", "item12", "item13", "item14", "item15", "item16"));
  recyclerview.setlayoutmanager(new linearlayoutmanager(this,linearlayoutmanager.vertical,false));
  simpleadapter adapter = new simpleadapter(items);
  recyclerview.setadapter(adapter);
  itemtouchhelper helper = new itemtouchhelper(new myitemtouchcallback(adapter));
  helper.attachtorecyclerview(recyclerview);
}

 实现itemtouchhelper.callback 接口后有三个方法需要重写：

getmovementflags(recyclerview recyclerview, recyclerview.viewholder viewholder) ：设置滑动类型的标记。需要设置两种类型的 flag ，即 dragflags 和 swipeflags ，分别代表着拖拽标记和滑动标记。最后需要调用 makemovementflags(dragflags,
 swipeflags)方法来合成返回。
onmove(recyclerview recyclerview, recyclerview.viewholder viewholder, recyclerview.viewholder target) ：当用户拖拽列表某个 item 时会回调。很明显，拖拽排序的代码应该在这个方法中实现。

onswiped(recyclerview.viewholder viewholder, int direction) ：当用户滑动列表某个 item 时会回调。所以侧滑删除的代码应该在这个方法中实现。
下面是重写的几个方法：

第一个，getmovementflags方法

@override
public int getmovementflags(recyclerview recyclerview, recyclerview.viewholder viewholder) {
  int dragflag;
  int swipeflag;
  recyclerview.layoutmanager manager = recyclerview.getlayoutmanager();
  if (manager instanceof gridlayoutmanager){
    dragflag = itemtouchhelper.down | itemtouchhelper.up | itemtouchhelper.left | itemtouchhelper.right;
    swipeflag = 0;
  }else{
    dragflag = itemtouchhelper.down | itemtouchhelper.up;
    swipeflag = itemtouchhelper.end | itemtouchhelper.start;
  }

  return makemovementflags(dragflag,swipeflag);
}

这个方法里面根据layoutmanager分了两种情况，根据自己的情况去分
在gridlayoutmanager中只能上下左右拖拽但是不能侧滑删除，所以swipflag = 0；swipeflag的值itemtouchhelper.end是右滑删除，itemtouchhelper.start是左滑删除
最后调用makemovementflags方法合成返回

第二个，onmove方法

@override
public boolean onmove(recyclerview recyclerview, recyclerview.viewholder viewholder, recyclerview.viewholder target) {
  int fromposition = viewholder.getadapterposition();
  int toposition = target.getadapterposition();
  if (fromposition < toposition ){
    for (int i = fromposition ;i<toposition ;i++){
      collections.swap(adapter.getdatalist(),i,i+1);
    }
  }else{
    for (int i= fromposition; i>toposition; i--){
      collections.swap(adapter.getdatalist(),i ,i-1);
    }
  }
  recyclerview.getadapter().notifyitemmoved(fromposition,toposition);
  return true;
}

这个方法是用户在拖拽 item 的时候调用。所以关于列表排序的代码应该写在这里。方法参数中的 viewholder 代表的是用户当前拖拽的 item ，而 target 代表的是被用户拖拽所覆盖的那个 item 。所以在 onmove(recyclerview recyclerview, recyclerview.viewholder viewholder, recyclerview.viewholder target) 方法中的逻辑就是把 fromposition 至 toposition 为止改变它们的位置。

第三个，onswiped方法

@override
public void onswiped(recyclerview.viewholder viewholder, int direction) {
  int position = viewholder.getadapterposition();
  if (direction == itemtouchhelper.end | direction==itemtouchhelper.start){
    adapter.getdatalist().remove(position);
    adapter.notifyitemremoved(position);
  }
}

这个方法是在用户侧滑的时候调用的 ，在里面对adapter的数据进行删除就可以了

最后两个方法

 @override
  public void onselectedchanged(recyclerview.viewholder viewholder, int actionstate) {
    super.onselectedchanged(viewholder, actionstate);
    if (actionstate==itemtouchhelper.action_state_drag){
      viewholder.itemview.setbackgroundcolor(color.blue);
    }

  }

  @override
  public void clearview(recyclerview recyclerview, recyclerview.viewholder viewholder) {
    super.clearview(recyclerview, viewholder);
    viewholder.itemview.setbackgroundcolor(0);
  }
}

就是优化的方法，第一个是选择条目改变状态，第二个是手指抬起之后恢复条目状态

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。