自己定义滑动删除item的ListView。

Posted 2020-09-13 yangykaifa

首先继承创建继承ListView和实现OnTouchListener,OnGestureListener的类。

会使用到AbsList中的pointToPosition(int x, int y)方法。这种方法主要是依据点击的位置获取点击行的在列表中的索引。

还有ViewGroup中的getChildAt(int index)方法，主要用于依据当前的索引获取子控件。这个（这个索引以可见屏幕顶端開始）。

之所以实现OnTouchListener,OnGestureListener。是由于OnGestureListener要获取到OnTouchListener传递的事件。

package com.example.mylistview;

import android.content.Context;
import android.util.AttributeSet;
import android.widget.ListView;
import android.widget.RelativeLayout;
import android.widget.Toast;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.ViewGroup;

public class MyListView extends ListView implements OnTouchListener,OnGestureListener
{
	private GestureDetector gestureDetector;
	private View deleteButton;
	private ViewGroup itemLayout;
	private onDeleteListener listener;
	private int selectedItem;
	private boolean isDeleteShown;
	private Context lcontext;

	public void setonDeleteListener(onDeleteListener l)
	{
		listener = l;
	}
	//回调接口
	public interface onDeleteListener
	{
		void onDelete(int index);
	}
	
	public MyListView(Context context, AttributeSet attrs) {
		super(context, attrs);
		gestureDetector = new GestureDetector(getContext(), this);
		lcontext = context;
		setOnTouchListener(this);
	}
	
	//事件的传入口。分发事件给gestureDetector。
	@Override
	public boolean onTouch(View v, MotionEvent event) {
		if(isDeleteShown)
		{
			itemLayout.removeView(deleteButton);
			deleteButton = null;
			isDeleteShown = false;
			return false;
		}
		return gestureDetector.onTouchEvent(event);
	}
	
	@Override
	public boolean onDown(MotionEvent e) {
		if(!isDeleteShown)
		{
			//所按下位置的行数
			selectedItem = pointToPosition((int)e.getX(),(int) e.getY());
		}
		return true;
	}
	
	//处理滑动事件
	@Override
	public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
			float velocityY) {
		//假设按钮没有显示而且在x轴上的速度大于在y轴上的速度
		if(!isDeleteShown && Math.abs(velocityX) > Math.abs(velocityY))
		{
			deleteButton = LayoutInflater.from(getContext()).inflate(R.layout.delete_button, null);
			deleteButton.setOnClickListener(new OnClickListener() {
				
				@Override
				public void onClick(View v) {
					itemLayout.removeView(deleteButton);
					deleteButton = null;
					isDeleteShown = false;
					listener.onDelete(selectedItem);
				}
			});
			//（从当前页面可见的開始）获取一行的布局
			itemLayout = (ViewGroup) getChildAt(selectedItem - getFirstVisiblePosition());
			if(itemLayout == null)
			{
				Toast.makeText(lcontext, "请选择可用的行。", Toast.LENGTH_SHORT).show();
				return false;
			}
			//设置button的加入參数
			RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);
			params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
			params.addRule(RelativeLayout.CENTER_VERTICAL);
			itemLayout.addView(deleteButton, params);
			isDeleteShown = true;
		}
		return true;
	}

	@Override
	public void onShowPress(MotionEvent e) {
		// TODO Auto-generated method stub
		
	}

	@Override
	public boolean onSingleTapUp(MotionEvent e) {
		// TODO Auto-generated method stub
		return false;
	}

	@Override
	public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
			float distanceY) {
		// TODO Auto-generated method stub
		return false;
	}

	@Override
	public void onLongPress(MotionEvent e) {
		// TODO Auto-generated method stub
		
	}

}

之后定义删除按钮布局。和主界面的布局。item布局。

自己定义adapter：

package com.example.mylistview;

import java.util.List;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

public class MyAdapter extends ArrayAdapter<String> 
{

	public MyAdapter(Context context, int resource, List<String> objects) {
		super(context, resource, objects);
		// TODO Auto-generated constructor stub
	}
	
	@Override
	public View getView(int position,View convertView,ViewGroup parent)
	{
		View view;
		if(convertView == null)
		{
			view = LayoutInflater.from(getContext()).inflate(R.layout.list_view_item, null);
		}
		else
		{
			view = convertView;
		}
		TextView tv = (TextView)view.findViewById(R.id.text_view);
		tv.setText(getItem(position));
		return view;
		
	}

}

主界面代码：

</pre><pre name="code" class="java">package com.example.mylistview;

import java.util.ArrayList;
import java.util.List;

import com.example.mylistview.MyListView.onDeleteListener;

import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.Window;
import android.app.Activity;

public class MainActivity extends Activity 
{
	MyListView myList;
	MyAdapter adapter;
	private List<String> list = new ArrayList<String>();
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		requestWindowFeature(Window.FEATURE_NO_TITLE);		
		setContentView(R.layout.activity_main);
		initList();
		myList = (MyListView)findViewById(R.id.myList);
		//传入接口，并实现对应的方法
		myList.setonDeleteListener(new onDeleteListener() {
			@Override
			//依据回调传回来的item索引删除对应的行
			public void onDelete(int index) {
				list.remove(index);
				adapter.notifyDataSetChanged();
			}
		});
		adapter = new MyAdapter(this, 0, list);
	myList.setAdapter(adapter);
	}
	private void initList() {
		list.clear();
		list.add("item 1");
		list.add("item 2");
		list.add("item 3");
		list.add("item 4");
		list.add("item 5");
		list.add("item 6");
		list.add("item 7");
		list.add("item 8");
		list.add("item 9");
		list.add("item 10");
		list.add("item 11");
		list.add("item 12");
		list.add("item 13");
		list.add("item 14");
		list.add("item 15");
	}
	@Override
	public boolean onCreateOptionsMenu(Menu menu)
	{
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}
	@Override
	public boolean onOptionsItemSelected(MenuItem item)
	{
		if(item.getItemId() == R.id.reLoad)
		{
			initList();
			adapter.notifyDataSetChanged();
		}
		return true;
	}
}