listView中多個listItem佈局時，convertView快取及使用

但是如果出現如下圖的需求，convertView就不太好用了，convertView在Item為單一的佈局時，能夠回收並重用，但是多個Item佈局時，convertView的回收和重用會出現問題。





官網解釋如下，不解釋了
Get the type of View that will be created by getView(int, android.view.View, android.view.ViewGroup)]getView(int, View, ViewGroup) for the specified item.

Parameters

position

The position of the item within the adapter's data set whose view type we want.

Returns

• 
  
  
• An integer representing the type of View. Two views should share the same type if one can be converted to the other in getView(int, android.view.View, android.view.ViewGroup)getView(int, View, ViewGroup). Note: Integers must be in the range 0 to getViewTypeCount() - 1. IGNORE_ITEM_VIEW_TYPE can also be returned.
  

Get the type of View that will be created by getView(int, android.view.View, android.view.ViewGroup)getView(int, View, ViewGroup） for the specified item.

Parameters

position

The position of the item within the adapter's data set whose view type we want.

Returns

• 
  
  
• An integer representing the type of View. Two views should share the same type if one can be converted to the other in getView(int, android.view.View, android.view.ViewGroup)getView(int, View, ViewGroup). Note: Integers must be in the range 0 to getViewTypeCount() - 1. IGNORE_ITEM_VIEW_TYPE can also be returned.
  

1. package com.bestv.listViewTest;
   
2. 
   
3. import java.util.ArrayList;
   
4. 
   
5. import android.app.Activity;
   
6. import android.content.Context;
   
7. import android.os.Bundle;
   
8. import android.util.Log;
   
9. import android.view.LayoutInflater;
   
10. import android.view.View;
    
11. import android.view.ViewGroup;
    
12. import android.widget.BaseAdapter;
    
13. import android.widget.CheckBox;
    
14. import android.widget.ImageView;
    
15. import android.widget.LinearLayout;
    
16. import android.widget.ListView;
    
17. import android.widget.TextView;
    
18. 
    
19. public class listViewTest extends Activity {
    
20. /** Called when the activity is first created. */
    
21. ListView listView;
    
22. MyAdapter listAdapter;
    
23. ArrayList<String> listString;
    
24. 
    
25. @Override
    
26. public void onCreate(Bundle savedInstanceState) {
    
27. super.onCreate(savedInstanceState);
    
28. setContentView(R.layout.main);
    
29. listView = (ListView)this.findViewById(R.id.listview);
    
30. listString = new ArrayList<String>();
    
31. for(int i = 0 ; i < 100 ; i++)
    
32. {
    
33. listString.add(Integer.toString(i));
    
34. }
    
35. listAdapter = new MyAdapter(this);
    
36. listView.setAdapter(listAdapter);
    
37. }
    
38. 
    
39. class MyAdapter extends BaseAdapter{
    
40. 
    
41. Context mContext;
    
42. LinearLayout linearLayout = null;
    
43. LayoutInflater inflater;
    
44. TextView tex;
    
45. final int VIEW_TYPE = 3;
    
46. final int TYPE_1 = 0;
    
47. final int TYPE_2 = 1;
    
48. final int TYPE_3 = 2;
    
49. 
    
50. public MyAdapter(Context context) {
    
51. // TODO Auto-generated constructor stub
    
52. mContext = context;
    
53. inflater = LayoutInflater.from(mContext);
    
54. }
    
55. 
    
56. @Override
    
57. public int getCount() {
    
58. // TODO Auto-generated method stub
    
59. return listString.size();
    
60. }
    
61. 
    
62. //每個convert view都會呼叫此方法，獲得當前所需要的view樣式
    
63. @Override
    
64. public int getItemViewType(int position) {
    
65. // TODO Auto-generated method stub
    
66. int p = position%6;
    
67. if(p == 0)
    
68. return TYPE_1;
    
69. else if(p < 3)
    
70. return TYPE_2;
    
71. else if(p < 6)
    
72. return TYPE_3;
    
73. else
    
74. return TYPE_1;
    
75. 
    
76. }
    
77. 
    
78. @Override
    
79. public int getViewTypeCount() {
    
80. // TODO Auto-generated method stub
    
81. return 3;
    
82. }
    
83. 
    
84. @Override
    
85. public Object getItem(int arg0) {
    
86. // TODO Auto-generated method stub
    
87. return listString.get(arg0);
    
88. }
    
89. 
    
90. @Override
    
91. public long getItemId(int position) {
    
92. // TODO Auto-generated method stub
    
93. return position;
    
94. }
    
95. 
    
96. @Override
    
97. public View getView(int position, View convertView, ViewGroup parent) {
    
98. // TODO Auto-generated method stub
    
99. viewHolder1 holder1 = null;
    
100. viewHolder2 holder2 = null;
     
101. viewHolder3 holder3 = null;
     
102. int type = getItemViewType(position);
     
103. 
     
104. 
     
105. //無convertView，需要new出各個控制元件
     
106. if(convertView == null)
     
107. { 
     
108. Log.e("convertView = ", " NULL");
     
109. 
     
110. //按當前所需的樣式，確定new的佈局
     
111. switch(type)
     
112. {
     
113. case TYPE_1:
     
114. convertView = inflater.inflate(R.layout.listitem1, parent, false);
     
115. holder1 = new viewHolder1();
     
116. holder1.textView = (TextView)convertView.findViewById(R.id.textview1);
     
117. holder1.checkBox = (CheckBox)convertView.findViewById(R.id.checkbox);
     
118. Log.e("convertView = ", "NULL TYPE_1");
     
119. convertView.setTag(holder1);
     
120. break;
     
121. case TYPE_2:
     
122. convertView = inflater.inflate(R.layout.listitem2, parent, false);
     
123. holder2 = new viewHolder2();
     
124. holder2.textView = (TextView)convertView.findViewById(R.id.textview2);
     
125. Log.e("convertView = ", "NULL TYPE_2");
     
126. convertView.setTag(holder2);
     
127. break;
     
128. case TYPE_3:
     
129. convertView = inflater.inflate(R.layout.listitem3, parent, false);
     
130. holder3 = new viewHolder3();
     
131. holder3.textView = (TextView)convertView.findViewById(R.id.textview3);
     
132. holder3.imageView = (ImageView)convertView.findViewById(R.id.imageview);
     
133. Log.e("convertView = ", "NULL TYPE_3");
     
134. convertView.setTag(holder3);
     
135. break;
     
136. }
     
137. }
     
138. else
     
139. {
     
140. //有convertView，按樣式，取得不用的佈局
     
141. switch(type)
     
142. {
     
143. case TYPE_1:
     
144. holder1 = (viewHolder1) convertView.getTag();
     
145. Log.e("convertView !!!!!!= ", "NULL TYPE_1");
     
146. break;
     
147. case TYPE_2:
     
148. holder2 = (viewHolder2) convertView.getTag();
     
149. Log.e("convertView !!!!!!= ", "NULL TYPE_2");
     
150. break;
     
151. case TYPE_3:
     
152. holder3 = (viewHolder3) convertView.getTag();
     
153. Log.e("convertView !!!!!!= ", "NULL TYPE_3");
     
154. break;
     
155. }
     
156. }
     
157. 
     
158. //設定資源
     
159. switch(type)
     
160. {
     
161. case TYPE_1:
     
162. holder1.textView.setText(Integer.toString(position));
     
163. holder1.checkBox.setChecked(true);
     
164. break;
     
165. case TYPE_2:
     
166. holder2.textView.setText(Integer.toString(position));
     
167. break;
     
168. case TYPE_3:
     
169. holder3.textView.setText(Integer.toString(position));
     
170. holder3.imageView.setBackgroundResource(R.drawable.icon);
     
171. break;
     
172. }
     
173. 
     
174. 
     
175. return convertView;
     
176. }
     
177. 
     
178. }
     
179. 
     
180. 
     
181. //各個佈局的控制元件資源
     
182. 
     
183. class viewHolder1{
     
184. CheckBox checkBox;
     
185. TextView textView;
     
186. }
     
187. class viewHolder2{
     
188. TextView textView;
     
189. }
     
190. class viewHolder3{
     
191. ImageView imageView;
     
192. TextView textView;
     
193. }
     
194. }
     

複製程式碼

     在getView()中需要將不同佈局進行快取和適配，系統在判斷是否有convertView時，會自動去呼叫getItemViewType (int position) ，檢視是否已經有快取的該型別的佈局，從而進入if(convertView == null)和else{}的判斷。期間需要做的是convertView.setTag(holder3)，以便在convertView重用時可以直接拿到該佈局的控制元件，holder3 = (viewHolder3) convertView.getTag()。到這一步，convertView的回收和重用就已經寫好了，接下來只需要對你的不同的控制元件進行設定就行了。

如有不正確或者我理解錯誤的地方，大家輕拍！