Android中怎么实现可拖拽列表和多选功能

Android中怎么实现可拖拽列表和多选功能，很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。

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主窗口JAVA代码

/** * 编辑状态下长按拖动条目 * 1.通过ItemTouchHelper.Callback实现长按拖动 * 2.通过isEditable的值判断是否编辑状态，初值是false * 3.切换编辑状态要把isEditable的值取反，并改变复选框图标状态 * 4.在编辑状态下，按返回键回到非编辑状态 * 5.RecyclerView的点击事件通过RecyclerAdapter.Callback实现 */public class ReportListActivity extends AppCompatActivity implements View.OnClickListener { private static final String TAG = "ReportListActivity"; @BindView(R.id.tv_title_middle) TextView title; @BindView(R.id.title_left) ImageView backButton; @BindView(R.id.online_report_listview) RecyclerView mRecyclerView; @BindView(R.id.edit_tv) TextView edit; @BindView(R.id.filter_tv) TextView filter; @BindView(R.id.btn_delete) TextView delete; @BindView(R.id.btn_release) TextView release; @BindView(R.id.btn_close) TextView close; @BindView(R.id.btn_top) TextView top; @BindView(R.id.toolbar) LinearLayout mToolbar; private Context mContext; private boolean isEditable; private RecyclerAdapter mAdapter; private List mClsOnlineReportList; private ItemTouchHelper itemTouchHelper; @Override protected void onCreate(@Nullable Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_online_report);  ButterKnife.bind(this);  initView();  initData();  initListener(); } private void initData() {  mContext = this;  mClsOnlineReportList = new ArrayList<>();  mAdapter = new RecyclerAdapter(mClsOnlineReportList);  mRecyclerView.setAdapter(mAdapter);  getOfflineData(20);  //初始状态为非编辑模式  setIsEditable(false);  //初始化拖动接口  OnlineReportListCallback callback = new OnlineReportListCallback(mAdapter);  itemTouchHelper = new ItemTouchHelper(callback);  //初始状态为不可拖动  setRecyclerViewDraggable(false); } //生成模拟数据 private void getOfflineData(int num) {  List clsOnlineReportList = new ArrayList<>();  for (int i = 0; i < num; i++) {   ClsOnlineReport onlineReport = new ClsOnlineReport();   onlineReport.setActiveDate("activeDate " + i);   onlineReport.setAutoCloseDate("autoCloseDate " + i);   onlineReport.setBulletinID("bulletinID " + i);   onlineReport.setBulletinTime("bulletinTime " + i);   onlineReport.setBulletinTitle("bulletinTitle " + i);   onlineReport.setCreater("creater " + i);   clsOnlineReportList.add(onlineReport);  }  mClsOnlineReportList.addAll(clsOnlineReportList);  mAdapter.notifyDataSetChanged(); } private void initView() {  title.setText("可拖拽列表");  edit.setVisibility(View.VISIBLE);  mToolbar.setVisibility(View.GONE);  //设置RecyclerView的布局  mRecyclerView.setLayoutManager(new LinearLayoutManager(mContext)); } private void initListener() {  filter.setOnClickListener(this);  backButton.setOnClickListener(this);  edit.setOnClickListener(this);  delete.setOnClickListener(this);  release.setOnClickListener(this);  close.setOnClickListener(this);  top.setOnClickListener(this);  mAdapter.setmCallback((v, position) -> {   switch (v.getId()) {    case R.id.view_parent_1:    case R.id.view_parent_2:     ClsOnlineReport clsOnlineReport = mClsOnlineReportList.get(position);     //在编辑模式下，点击条目切换显示checkbox，并且判断选中条目的数量，     if (getIsEditable()) {      if (clsOnlineReport.getIsCheckBoxVisible()) {       clsOnlineReport.setIsChecked(!clsOnlineReport.getIsChecked());       mAdapter.notifyDataSetChanged();      }      for (int i = 0; i < mClsOnlineReportList.size(); i++) {       //数量等于0，隐藏工具条，否则显示工具条       ClsOnlineReport onlineReport = mClsOnlineReportList.get(i);       if (onlineReport.getIsChecked()) {        mToolbar.setVisibility(View.VISIBLE);        break;       }       if (i == mClsOnlineReportList.size() - 1) {        mToolbar.setVisibility(View.GONE);       }      }     } else {      //在非编辑模式下，点击条目直接跳转详情页，并把bulletinID传过去      Intent intent = new Intent(mContext, ReportDetailActivity.class);      intent.putExtra("bulletinID", clsOnlineReport.getBulletinID());      startActivityForResult(intent, 16371);     }   }  }); } @Override public void onBackPressed() {  //编辑状态下，按返回键回到非编辑状态，否则退出  if (getIsEditable()) {   switchEditable();  } else {   finish();  } } @Override public void onClick(View v) {  //编辑状态下，按返回键回到非编辑状态，否则退出  if (v.getId() == R.id.title_left) {   if (getIsEditable()) {    switchEditable();   } else {    finish();   }  }  //点击编辑按钮切换编辑状态  if (v.getId() == R.id.edit_tv) {   switchEditable();  }  //工具条的按钮对应不同的接口  switch (v.getId()) {   case R.id.btn_top:   case R.id.btn_close:   case R.id.btn_release:   case R.id.btn_delete:    Toast.makeText(mContext, "在此处调用接口", Toast.LENGTH_SHORT).show();  } } private void switchEditable() {  //将属性取反  setIsEditable(!getIsEditable());  //遍历列表并赋值  for (ClsOnlineReport clsOnlineReport : mClsOnlineReportList) {   clsOnlineReport.setIsCheckBoxVisible(getIsEditable());   clsOnlineReport.setIsChecked(false);  }  //通知适配器刷新  mAdapter.notifyDataSetChanged();  //隐藏工具条  mToolbar.setVisibility(View.GONE);  //切换拖动状态  setRecyclerViewDraggable(getIsEditable()); } public boolean getIsEditable() {  return isEditable; } public void setIsEditable(boolean isEditable) {  this.isEditable = isEditable; } //设置能否拖动 private void setRecyclerViewDraggable(boolean draggable) {  if (draggable) {   itemTouchHelper.attachToRecyclerView(mRecyclerView);  } else {   itemTouchHelper.attachToRecyclerView(null);  } } @Override protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {  //当详情页的数据有变动则刷新列表  if (requestCode == 16371 && resultCode == RESULT_OK) {   refreshData();  }  super.onActivityResult(requestCode, resultCode, data); } private void refreshData() {  Toast.makeText(mContext, "在此处调用接口", Toast.LENGTH_SHORT).show(); }}

适配器代码

/** * 可拖拽列表的适配器， * 1.需要实现OnlineReportListCallback.ItemTouchMoveListener * 2.持有一个接口用于传递position */public class RecyclerAdapter extends RecyclerView.Adapter implements OnlineReportListCallback.ItemTouchMoveListener, View.OnClickListener { private List mList; private Callback mCallback; public RecyclerAdapter(List mList) {  this.mList = mList; } public void setmCallback(Callback mCallback) {  this.mCallback = mCallback; } @Override public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {  LayoutInflater inflater = LayoutInflater.from(parent.getContext());  View v = inflater.inflate(R.layout.item_report_list, parent, false);  return new ItemHolder(v); } @Override public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {  ClsOnlineReport clsOnlineReport = mList.get(position);  ItemHolder itemHolder = (ItemHolder) holder;  if (clsOnlineReport.getIsCheckBoxVisible()) {   itemHolder.checkbox.setVisibility(View.VISIBLE);   itemHolder.drag.setVisibility(View.VISIBLE);  } else {   itemHolder.checkbox.setVisibility(View.GONE);   itemHolder.drag.setVisibility(View.GONE);  }  if (clsOnlineReport.getIsChecked()) {   itemHolder.checkbox.setImageResource(R.drawable.ic_check_box_black_24dp);  } else {   itemHolder.checkbox.setImageResource(R.drawable.ic_check_box_outline_blank_black_24dp);  }  itemHolder.parent1.setTag(position);  itemHolder.parent2.setTag(position);  itemHolder.parent1.setOnClickListener(this);  itemHolder.parent2.setOnClickListener(this);  itemHolder.time.setText(clsOnlineReport.getBulletinTime());  itemHolder.title.setText(clsOnlineReport.getBulletinTitle());  itemHolder.author.setText(clsOnlineReport.getCreater()); } @Override public int getItemCount() {  return mList.size(); } @Override public boolean onItemMove(int fromPosition, int toPosition) {  Collections.swap(mList, fromPosition, toPosition);  notifyItemMoved(fromPosition, toPosition);  return true; } class ItemHolder extends RecyclerView.ViewHolder {  @BindView(R.id.online_report_time)  TextView time;  @BindView(R.id.online_report_title)  TextView title;  @BindView(R.id.online_report_author)  TextView author;  @BindView(R.id.online_report_drag)  ImageView drag;  @BindView(R.id.online_report_checkbox)  ImageView checkbox;  @BindView(R.id.view_parent_1)  LinearLayout parent1;  @BindView(R.id.view_parent_2)  LinearLayout parent2;  ItemHolder(View itemView) {   super(itemView);   ButterKnife.bind(this, itemView);  } } @Override public void onClick(View v) {  mCallback.onClick(v, (int) v.getTag()); } public interface Callback {  void onClick(View v, int position); }}

需要实现的接口

/** * 用来完成RecyclerView长按拖拽的关键接口 * 1.getMovementFlags里面表示设置为上下拖动 * 2.onSelectedChanged里面表示拖动状态下改变背景色，拖动完成后恢复背景色 * 3.拖动完成的时候viewHolder的值为空！！！所以要用srcHolder */public class OnlineReportListCallback extends ItemTouchHelper.Callback { private ColorDrawable drawable; private RecyclerView.ViewHolder srcHolder; public interface ItemTouchMoveListener {  boolean onItemMove(int fromPosition, int toPosition); } private ItemTouchMoveListener moveListener; public OnlineReportListCallback(ItemTouchMoveListener moveListener) {  this.moveListener = moveListener;  int rgb = Color.rgb(0xff, 0xff, 0xff);  drawable = new ColorDrawable(rgb); } @Override public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {  int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;  return makeMovementFlags(dragFlags, ItemTouchHelper.ACTION_STATE_IDLE); } @Override public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder srcHolder, RecyclerView.ViewHolder targetHolder) {  this.srcHolder = srcHolder;  return srcHolder.getItemViewType() == targetHolder.getItemViewType() && moveListener.onItemMove(srcHolder.getAdapterPosition(), targetHolder.getAdapterPosition()); } @Override public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) { } @Override public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {  super.onSelectedChanged(viewHolder, actionState);  if (actionState == ItemTouchHelper.ACTION_STATE_DRAG) {   viewHolder.itemView.setBackground(null);  }  if (actionState == ItemTouchHelper.ACTION_STATE_IDLE) {   srcHolder.itemView.setBackground(drawable);  } }}

图片使用Android Studio内置的SVG，引入了ButterKnife绑定控件，另外内部类使用了lambda表达式折叠了，重点说一下RecyclerAdapter.Callback，这个接口的内部方法 void onClick(View v, int position) 是在View.OnClickListener的void onClick(View v)的基础上多传了一个参数，这个参数是放在tag里面的，其他难点注释里面都有

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