• Listview中显示不同的视图布局


    为了表示诚意,先上效果图再上源码,如今的技术文章没有demo,都是扯淡!!!!!!
    先看一张效果图:

    源码下载:http://files.cnblogs.com/files/fancing/BaseAdapterTest.rar.rar

    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; 
      } 
    }

    参考2:http://www.tuicool.com/articles/MBvABz
    参考3:http://blog.csdn.net/xyz_lmn/article/details/13745489
    参考4:http://blog.sina.com.cn/s/blog_629b701e0100x338.html

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  • 原文地址:https://www.cnblogs.com/fancing/p/6394217.html
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