Android Listview中显示不同的视图布局
1. 使用场景
在重写ListView的BaseAdapter时，我们常常在getView()方法中复用convertView，以提高性能。convertView在Item为单一的同种类型布局时，能够回收并重用，但是多个Item布局类型不同时，convertView的回收和重用会出现问题。比如有些行为纯文本，有些行则是图文混排，这里纯文本行为一类布局，图文混排的行为第二类布局。单一类型的ListView很简单，下面着重介绍一下ListView包含多种类型视图布局的情形。
2.ListView包含不同Item的布局
我们需要做这些工作:
1）重写 getViewTypeCount() – 该方法返回多少个不同的布局 2）重写 getItemViewType(int) – 根据position返回相应的Item 3）根据view item的类型，在getView中创建正确的convertView
3.案例
import java.util.ArrayList; import android.app.Activity; import android.content.Context; import android.os.Bundle; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.CheckBox; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.ListView; import android.widget.TextView; public class listViewTest extends Activity { /** Called when the activity is first created. */ ListView listView; MyAdapter listAdapter; ArrayList<String> listString; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); listView = (ListView)this.findViewById(R.id.listview); listString = new ArrayList<String>(); for(int i = 0 ; i < 100 ; i++) { listString.add(Integer.toString(i)); } listAdapter = new MyAdapter(this); listView.setAdapter(listAdapter); } class MyAdapter extends BaseAdapter{ Context mContext; LinearLayout linearLayout = null; LayoutInflater inflater; TextView tex; final int VIEW_TYPE = 3; final int TYPE_1 = 0; final int TYPE_2 = 1; final int TYPE_3 = 2; public MyAdapter(Context context) { // TODO Auto-generated constructor stub mContext = context; inflater = LayoutInflater.from(mContext); } @Override public int getCount() { // TODO Auto-generated method stub return listString.size(); } //每个convert view都会调用此方法，获得当前所需要的view样式 @Override public int getItemViewType(int position) { // TODO Auto-generated method stub int p = position%6; if(p == 0) return TYPE_1; else if(p < 3) return TYPE_2; else if(p < 6) return TYPE_3; else return TYPE_1; } @Override public int getViewTypeCount() { // TODO Auto-generated method stub return 3; } @Override public Object getItem(int arg0) { // TODO Auto-generated method stub return listString.get(arg0); } @Override public long getItemId(int position) { // TODO Auto-generated method stub return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { // TODO Auto-generated method stub viewHolder1 holder1 = null; viewHolder2 holder2 = null; viewHolder3 holder3 = null; int type = getItemViewType(position); //无convertView，需要new出各个控件 if(convertView == null) { Log.e("convertView = ", " NULL"); //按当前所需的样式，确定new的布局 switch(type) { case TYPE_1: convertView = inflater.inflate(R.layout.listitem1, parent, false); holder1 = new viewHolder1(); holder1.textView = (TextView)convertView.findViewById(R.id.textview1); holder1.checkBox = (CheckBox)convertView.findViewById(R.id.checkbox); Log.e("convertView = ", "NULL TYPE_1"); convertView.setTag(holder1); break; case TYPE_2: convertView = inflater.inflate(R.layout.listitem2, parent, false); holder2 = new viewHolder2(); holder2.textView = (TextView)convertView.findViewById(R.id.textview2); Log.e("convertView = ", "NULL TYPE_2"); convertView.setTag(holder2); break; case TYPE_3: convertView = inflater.inflate(R.layout.listitem3, parent, false); holder3 = new viewHolder3(); holder3.textView = (TextView)convertView.findViewById(R.id.textview3); holder3.imageView = (ImageView)convertView.findViewById(R.id.imageview); Log.e("convertView = ", "NULL TYPE_3"); convertView.setTag(holder3); break; } }else{ //有convertView，按样式，取得不用的布局 switch(type) { case TYPE_1: holder1 = (viewHolder1) convertView.getTag(); Log.e("convertView !!!!!!= ", "NULL TYPE_1"); break; case TYPE_2: holder2 = (viewHolder2) convertView.getTag(); Log.e("convertView !!!!!!= ", "NULL TYPE_2"); break; case TYPE_3: holder3 = (viewHolder3) convertView.getTag(); Log.e("convertView !!!!!!= ", "NULL TYPE_3"); break; } } //设置资源 switch(type) { case TYPE_1: holder1.textView.setText(Integer.toString(position)); holder1.checkBox.setChecked(true); break; case TYPE_2: holder2.textView.setText(Integer.toString(position)); break; case TYPE_3: holder3.textView.setText(Integer.toString(position)); holder3.imageView.setBackgroundResource(R.drawable.icon); break; } return convertView; } } //各个布局的控件资源 class viewHolder1{ CheckBox checkBox; TextView textView; } class viewHolder2{ TextView textView; } class viewHolder3{ ImageView imageView; TextView textView; } }
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失败是什么?没有什么.只是更走近成功一步,
