[android] ListView 选中状态的动态改变

曾经终败给现在 2022-08-10 18:30 251阅读 0赞

ListView 选中状态时改变背景，可以标识当前选中的是哪一个元素，在 继承 BaseAdapter 的类里实现。

1.MainActivity.java 里的相关代码：

private MyAdapter adapter = null ;
    list = (ListView) findViewById(R.id.listView1) ;//获取ListView
    		
    		adapter = new MyAdapter(MainActivity.this) ;
    		
    		list.setAdapter(adapter) ;
    		
    		list.setOnItemClickListener(new OnItemClickListener() {
    
    			@Override
    			public void onItemClick(AdapterView<?> arg0, View arg1, int position,long arg3) {
    				PlayMusicByNum(position) ;
    				adapter.setSelectItem(position) ;
    				adapter.notifyDataSetInvalidated() ;
    		}
    			
    }) ;

2.MyAdapter.java

package com.audioplayer.dao;
    
    import android.content.Context;
    import android.graphics.Color;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.BaseAdapter;
    import android.widget.ImageView;
    import android.widget.TextView;
    
    import com.audioplayer.bean.Music;
    import com.example.audioplayer.R;
    
    public class MyAdapter extends BaseAdapter {
    	
    	private int selectItem = -1 ;//选中的Item
    	private LayoutInflater myInflater ;
    	
    	MyAdapter(Context c) {
    		myInflater = LayoutInflater.from(c) ;
    	}
    	
    	@Override
    	public int getCount() {
    		return MainActivity.musicList.size() ;
    	}
    
    	@Override
    	public Object getItem(int position) {
    		return MainActivity.musicList.get(position).getTitle() ;
    	}
    
    	@Override
    	public long getItemId(int position) {
    		return position ;
    	}
    
    	@Override
    	public View getView(int position, View convertView, ViewGroup Groupparent) {
    		convertView = myInflater.inflate(R.layout.another_layout, null) ;
    		ImageView imgLogo = (ImageView) convertView.findViewById(R.id.imageView1) ;
    		TextView txtName = (TextView) convertView.findViewById(R.id.name) ;
    		TextView txtArtist = (TextView) convertView.findViewById(R.id.artist) ;
    		TextView txtDuration = (TextView) convertView.findViewById(R.id.duration) ;
    		
    		Music music = MainActivity.musicList.get(position) ;
    		
    		imgLogo.setImageResource(R.drawable.music) ;
    		txtName.setText(music.getTitle()) ;
    		txtArtist.setText(music.getArtist()) ;
    		txtDuration.setText( timeParse(music.getDuration()) ) ;
    		
    		if(position == selectItem){
    			convertView.setBackgroundColor(Color.CYAN) ;
    		}else{
    			convertView.setBackgroundColor(Color.TRANSPARENT) ;
    		}
    		
    		return convertView ;
    	}
    	
    	public void setSelectItem(int selectItem) {
    		this.selectItem = selectItem ;
    	}
    	
    	public static String timeParse(long duration) {//将毫秒数时间转化为“03:50”形式
    		String time = "" ;
    		
    		long minute = duration / 60000 ;
    		long seconds = duration % 60000 ;
    		
    		long second = Math.round((float)seconds/1000) ;
    		
    		if( minute < 10 ){
    			time += "0" ;
    		}
    		time += minute+":" ; 
    		
    		if( second < 10 ){
    			time += "0" ;
    		}
    		time += second ;
    		
    		return time ;
    	}
    	
    }