一些IM聊天软件的展现形式是左右分开的形式。比如说，别人给你发的信息全部靠左显示，你自己发给别人的信息全部靠右显示。
而我们的ListView很多时候是显示同一个布局，其实BaseAdapter中有2个重要的方法在大多数情况下我们并未使用到，一个是public int getViewTypeCount()，显示ListView中有多少种布局（默认是显示是1），像微信那样聊天界面，是有2种布局方式；另外一个getItemViewType()，可以让不同item条目加载不同的布局,下面就简单的模拟下微信的聊天界面做法：
MainActivity.java
1. package com.jackie.wechat;
2.
3. import java.util.ArrayList;
4. import java.util.List;
5.
6. import android.app.Activity;
7. import android.os.Bundle;
8. import android.view.LayoutInflater;
9. import android.view.View;
10. import android.view.ViewGroup;
11. import android.widget.BaseAdapter;
12. import android.widget.ListView;
13. import android.widget.TextView;
14.
15. public class MainActivity extends Activity {
16. private ListView mListView;
17. private List<Person> persons;
18. private int TYPE_COUNT = 2;
19. private int LEFT = 0;
20. private int RIGHT = 1;
21. private LayoutInflater mInflater;
22. private MyAdapter adapter;
23. @Override
24. protected void onCreate(Bundle savedInstanceState) {
25. super.onCreate(savedInstanceState);
26. setContentView(R.layout.activity_main);
27. mListView = (ListView) findViewById(R.id.listview);
28. mInflater = LayoutInflater.from(this);
29. initData();
30. new MyAdapter();
31. mListView.setAdapter(adapter);
32. }
33. private void initData() {
34. new ArrayList<Person>();
35. for(int i = 0; i < 40; i++){
36. new Person();
37. person.setAge(i);
38. person.setName("更深的蓝");
39. if(i % 2 == 0){
40. person.setType(0);
41. else {
42. person.setType(1);
43. }
44. person);
45. }
46. }
47.
48. privateclass MyAdapter extends BaseAdapter{
49.
50. @Override
51. public int getCount() {
52. return persons.size();
53. }
54.
55. @Override
56. public Object getItem(int position) {
57. return persons.get(position);
58. }
59.
60. @Override
61. public long getItemId(int position) {
62. return position;
63. }
64.
65. @Override
66. public int getItemViewType(int position) {
67. if(persons.get(position).getType() == 0){
68. return LEFT;
69. }
70. return RIGHT;
71. }
72.
73. @Override
74. public int getViewTypeCount() {
75. return TYPE_COUNT;
76. }
77.
78. @Override
79. public View getView(int position, View convertView, ViewGroup parent) {
80. ViewHolder mHolder;
81. Person person = persons.get(position);
82. if(getItemViewType(position) == LEFT) {
83. if (convertView == null) {
84. mHolder = new ViewHolder();
85. null);
86. mHolder.tv_username = (TextView) convertView.findViewById(R.id.tv_username);
87. mHolder.tv_age = (TextView) convertView.findViewById(R.id.tv_age);
88. mHolder);
89. else {
90. mHolder
91. }
92.
93. mHolder.tv_username.setText(person.getName());
94. mHolder.tv_age.setText(String.valueOf(person.getAge()));
95. else {
96. if(convertView == null){
97. mHolder = new ViewHolder();
98. null);
99. mHolder.tv_username = (TextView) convertView.findViewById(R.id.tv_username);
100. mHolder.tv_age = (TextView) convertView.findViewById(R.id.tv_age);
101. mHolder);
102. else{
103. mHolder = (ViewHolder) convertView.getTag();
104. }
105.
106. mHolder.tv_username.setText(person.getName());
107. mHolder.tv_age.setText(String.valueOf(person.getAge()));
108. }
109. return convertView;
110. }
111.
112. privateclass ViewHolder {
113. TextView tv_username;
114. TextView tv_age;
115. }
116. }
117. }
Person.java
1. package com.jackie.wechat;
2.
3. public class Person {
4. private String name;
5. private int age;
6. private int type;
7. public String getName() {
8. return name;
9. }
10.
11. public void setName(String name) {
12. this.name = name;
13. }
14.
15. public int getAge() {
16. return age;
17. }
18.
19. public void setAge(int age) {
20. this.age = age;
21. }
22. public int getType() {
23. return type;
24. }
25.
26. public void setType(int type) {
27. this.type = type;
28. }
29. }
item_left.xml
1. <?xml version="1.0" encoding="utf-8"?>
2. <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
3. android:layout_width="match_parent"
4. android:layout_height="match_parent"
5. android:orientation="vertical"
6. android:background="#ffffff"
7. >
8. <RelativeLayout
9. android:layout_width="fill_parent"
10. android:layout_height="45dp"
11. >
12. <TextView
13. android:id="@+id/tv_username"
14. android:layout_width="wrap_content"
15. android:layout_height="wrap_content"
16. android:textSize="16sp"
17. android:textColor="#123456"
18. android:layout_centerVertical="true"
19. android:layout_alignParentLeft="true"
20. />
21. <TextView
22. android:id="@+id/tv_age"
23. android:layout_width="wrap_content"
24. android:layout_height="wrap_content"
25. android:textSize="16sp"
26. android:textColor="#123456"
27. android:layout_centerVertical="true"
28. android:layout_toRightOf="@id/tv_username"
29. android:layout_marginLeft="20dp"
30. />
31. </RelativeLayout>
32. </RelativeLayout>
item_right.xml
1. <?xml version="1.0" encoding="utf-8"?>
2. <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
3. "match_parent"
4. "match_parent"
5. "vertical"
6. "#ffffff"
7. >
8. <RelativeLayout
9. "fill_parent"
10. "45dp"
11. >
12. <TextView
13. "@+id/tv_username"
14. "wrap_content"
15. "wrap_content"
16. "16sp"
17. "#123456"
18. "true"
19. "true"
20. />
21. <TextView
22. "@+id/tv_age"
23. "wrap_content"
24. "wrap_content"
25. "16sp"
26. "#123456"
27. "true"
28. "@id/tv_username"
29. "20dp"
30. />
31. </RelativeLayout>
32. </RelativeLayout>
