android左滑删除

android左滑出现删除按钮的场景比较常见，实现方式也有多种，这里采用比较简单的一种，即列表的item布局采用HorizontalScrollView，将正常展示的内容宽度设置为屏幕的宽度，删除按钮默认隐藏，通过滑动来显示或者隐藏删除按钮。item布局如下：

<?xml version="1.0" encoding="utf-8"?>
<HorizontalScrollView xmlns:android="http://schemas.android.com/apk/res/android"
                      xmlns:tools="http://schemas.android.com/tools"
                      android:layout_width="match_parent"
                      android:layout_height="wrap_content"
                      android:id="@+id/hsv"
                      android:scrollbars="none"
                      android:orientation="horizontal">

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:id="@+id/tv1"
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:background="#998"
            android:gravity="center"
            tools:text="998"
            />

        <TextView
            android:id="@+id/tv2"
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:background="#666"
            android:gravity="center"
            android:text="delete"
            />
    </LinearLayout>
</HorizontalScrollView>

列表采用Recyclerview，代码比较简单，一看就明白了，关键处在于adapter中onBindViewHolder的处理，见下面的代码：

public class Main2Activity extends AppCompatActivity {

    List<String> list = new ArrayList<>();
    private RvAdapter rvAdapter;
    private String[] items = new String[20];
    private int width;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        initData();
        final RecyclerView rv = findViewById(R.id.rv);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);
        rv.setLayoutManager(linearLayoutManager);
        rvAdapter = new RvAdapter(items);
        rv.setAdapter(rvAdapter);
        width = getWindowManager().getDefaultDisplay().getWidth();
    }

    private void initData() {
        for (int i = 0; i < 20; i++) {
            items[i] = Integer.toString(i);
        }
    }

    class RvAdapter extends RecyclerView.Adapter<RvAdapter.VH> {
        String[] items;

        public RvAdapter(String[] items) {
            this.items = items;
        }
        @NonNull
        @Override
        public VH onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            return new VH(LayoutInflater.from(Main2Activity.this).inflate(R.layout.scroll_item, parent, false));
        }

        @Override
        public void onBindViewHolder(@NonNull final VH holder, final int position) {
            //list用来记录itemView是否滑开，避免recyclerview复用出现bug
            if (list.contains(position + "")) {
                holder.itemView.scrollTo(holder.textDelete.getWidth(), 0);
            } else {
                holder.itemView.scrollTo(0, 0);
            }
            holder.text.setText(items[position]);
            //将item要展示的内容宽度设置为屏幕宽度，删除按钮则会隐藏在屏幕右侧
            ViewGroup.LayoutParams layoutParams = holder.text.getLayoutParams();
            layoutParams.width = width;
            holder.hsv.setOnTouchListener(new View.OnTouchListener() {
                @Override
                public boolean onTouch(View v, MotionEvent event) {
                    switch (event.getAction()) {
                        case MotionEvent.ACTION_UP:
                            //获取滑动的距离
                            int scrollX = holder.hsv.getScrollX();
                            //获取右侧删除按钮的宽度
                            int width = holder.textDelete.getWidth();
                            //如果滑动距离超过了删除按钮宽度的1/2，则将删除按钮滑出，否则隐藏
                            if (scrollX >= width / 2) {
                                holder.itemView.scrollTo(width, 0);
                                //滑动的item记录下来
                                list.add(position + "");
                            } else {
                                holder.itemView.scrollTo(0, 0);
                                if (list.contains(position + "")) {
                                    //记录中移除
                                    list.remove(position + "");
                                }
                            }
                            break;
                        case MotionEvent.ACTION_MOVE:

                            break;
                    }
                    //注意此处返回false
                    return false;
                }
            });
        }

        @Override
        public int getItemCount() {
            return items.length;
        }

        class VH extends RecyclerView.ViewHolder {

            private final TextView text;
            private final TextView textDelete;
            private final HorizontalScrollView hsv;

            public VH(View itemView) {
                super(itemView);
                text = itemView.findViewById(R.id.tv1);
                textDelete = itemView.findViewById(R.id.tv2);
                hsv = itemView.findViewById(R.id.hsv);
            }
        }
    }
}