Android：ListView、BaseAdapter、convertView、ListView优化及事件、notifyDataSetCh...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 @Override protected void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); setContentView(R.layout.activity_main); final ArrayList<String> title = new ArrayList<String>(); for ( int i = 0 ; i < 20 ; i++) { title.add( "标题" + i); } ListView listView = (ListView) findViewById(R.id.listView1); listView.setAdapter( new BaseAdapter() { @Override public View getView( int position, View convertView, ViewGroup parent) //执行数等于当前页面出现的行数,convertView指滚动消失的layout { Log.e( "getView" , "调用getView" + i++ + "convertView:" + convertView); LayoutInflater inf = getLayoutInflater(); //通过LayoutInflater将布局id转换到对象 RelativeLayout relativeLayout = (RelativeLayout) inf.inflate(R.layout.relat, null ); TextView titleview = (TextView) relativeLayout.findViewById(R.id.textView1); //通过布局找到里面的控件 titleview.setText(title.get(position)); //得到容器内的内容 return relativeLayout; } @Override public long getItemId( int position) { return 0 ; } @Override public Object getItem( int position) { return null ; } @Override //先执行getCount再执行getView，出现新行数时再次执行getCount //listview清单里要设置高度match_parent //每次点击屏幕一次都会先执行getCount public int getCount() { Log.e( "getCount" , "调用getCount" + j++); return title.size(); } }); } 复用converview： 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 ListView listView = (ListView) findViewById(R.id.listView1); listView.setAdapter( new BaseAdapter() { @Override public View getView( int position, View convertView, ViewGroup parent) //执行数等于当前页面出现的行数,convertView指滚动消失的layout { //复用converview RelativeLayout relativeLayout = null ; if (convertView == null ) { LayoutInflater inf = getLayoutInflater(); relativeLayout = (RelativeLayout) inf.inflate(R.layout.relat, null ); } else { relativeLayout = (RelativeLayout) convertView; } TextView titleView = (TextView) relativeLayout.findViewById(R.id.textView1); titleView.setText(title.get(position)); return relativeLayout; } 继续优化： 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 public class MainActivity extends Activity { int imID = 0 ; class Msg //内容 { String mTitle; String mSubtitle; String mTime; int mImagID; public Msg(String mTitle, String mSubtitle, String mTime, int mImagID) { super (); this .mTitle = mTitle; this .mSubtitle = mSubtitle; this .mTime = mTime; this .mImagID = mImagID; } } class ViewHolder //控件 { TextView viewTitle; TextView viewSubtitle; TextView viewTime; ImageView viewImage; } @Override protected void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); setContentView(R.layout.activity_main); Date timeNow = new Date(); SimpleDateFormat timeFormat = new SimpleDateFormat( "HH:mm:ss" ); String time = timeFormat.format(timeNow); final ArrayList<Msg> msgList = new ArrayList<Msg>(); for ( int i = 0 ; i < 30 ; i++) //选择图片 { if (i % 4 == 0 ) { imID = R.drawable.ic_launcher; } if (i % 4 == 1 ) { imID = R.drawable.ic_1; } if (i % 4 == 2 ) { imID = R.drawable.ic_2; } if (i % 4 == 3 ) { imID = R.drawable.ic_3; } Msg msg = new Msg( "标题" + i, "内容" + i, time ,imID); msgList.add(msg); } ListView listView = (ListView) findViewById(R.id.listView1); listView.setAdapter( new BaseAdapter() { ViewHolder holder = null ; @Override public View getView( int position, View convertView, ViewGroup parent) { RelativeLayout relout = null ; if (convertView == null ) //创建首页时才find控件 { LayoutInflater layoutInflater =getLayoutInflater(); relout = (RelativeLayout) layoutInflater.inflate(R.layout.relaout, null ); holder = new ViewHolder(); holder.viewTitle= (TextView) relout.findViewById(R.id.textView_title); holder.viewSubtitle = (TextView) relout.findViewById(R.id.textView_subtitle); holder.viewTime = (TextView) relout.findViewById(R.id.textView_time); holder.viewImage = (ImageView) relout.findViewById(R.id.imageView1); relout.setTag(holder); } else //否则复用layout和view { relout = (RelativeLayout) convertView; holder = (ViewHolder) relout.getTag(); //记得得到holder } Msg msg = msgList.get(position); holder.viewTitle.setText(msg.mTitle); holder.viewSubtitle.setText(msg.mSubtitle); holder.viewTime.setText(msg.mTime); holder.viewImage.setImageResource(msg.mImagID); //设置图片的方法 return relout; } @Override public long getItemId( int position) { return 0 ; } @Override public Object getItem( int position) { return null ; } @Override public int getCount() { return msgList.size(); } }); } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.activity_main, menu); return true ; } } 点击按钮更新listview：Adapter使用notifyDataSetChanged()通知listview更新 3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 private void btn1Click() //增加一行信息 { i++; data.add( "内容" + i ); arrAdapter.notifyDataSetChanged(); //Adapter通知listview做更新 } private void btn2Click() //删除第一行信息 { if (data.size() < 1 ) { Toast.makeText( this , "信息已删除完毕！" , Toast.LENGTH_LONG).show(); } else { data.remove( 0 ); arrAdapter.notifyDataSetChanged(); //Adapter通知listview做更新 } } private void btnsortClick() //对列表进行排序 { Collections.sort(data); arrAdapter.notifyDataSetChanged(); } 注： 1.LayoutInflater inflater = getLayoutInflater(); layout = (RelativeLayout) inflater.inflate(R.layout.relayout, null); layout要通过LayoutInflater拿到。 2.getView返回layout，getCount()返回int。 3.layout.getTag()要转换为holder = (ViewHolder)。 本文转自 glblong 51CTO博客，原文链接：http://blog.51cto.com/glblong/1201270，如需转载请自行联系原作者
