学习适配器有一段时间了,现在对BaseAdapter的优化和要是项目中用到的适配其很多的话,完全可以建立一个SimpleBaseAdapter(继承自BaseAdapter),方便扩展.
主布局代码:
1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 2 xmlns:tools="http://schemas.android.com/tools" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:orientation="vertical" 6 tools:context=".MainActivity"> 7 8 <ListView 9 android:id="@+id/listview" 10 android:layout_width="wrap_content" 11 android:layout_height="wrap_content" 12 /> 13 14 </LinearLayout>
item的布局:
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 android:layout_width="match_parent" 4 android:layout_height="wrap_content" 5 android:background="@drawable/bread__selector_pink_item" 6 android:orientation="horizontal" 7 android:gravity="center" 8 android:padding="10dp"> 9 10 <RelativeLayout 11 android:id="@+id/shop_info" 12 android:layout_width="fill_parent" 13 android:layout_height="wrap_content" 14 android:gravity="center_vertical" 15 android:paddingRight="12dp" 16 android:paddingLeft="12dp"> 17 18 <TextView 19 android:id="@+id/student_name" 20 android:layout_width="match_parent" 21 android:layout_height="wrap_content" 22 android:text="东海堂天河公园店" 23 android:textSize="14sp" /> 24 25 <TextView 26 android:id="@+id/student_addr" 27 android:layout_width="match_parent" 28 android:layout_height="wrap_content" 29 android:layout_below="@+id/student_name" 30 android:layout_marginTop="10dp" 31 android:text="广州天河区建业路华翠街" 32 android:textColor="@color/font_gray" 33 android:textSize="10sp" /> 34 35 </RelativeLayout> 36 37 </LinearLayout>
现在来说说BaseAdapter的优化,目前通用的优化就是ViewHolder,在getView()方法中,首次对convertView非空的处理,convertView会绑定一个ViewHolder对象，这个viewHolder主要用于帮convertView存储布局中的控件。了解这个就可以了.
来看看BaseAdapter的写法:
1 package com.fightzhao.myadapter1.ui.adapter;
2
3 import android.content.Context;
4 import android.view.LayoutInflater;
5 import android.view.View;
6 import android.view.ViewGroup;
7 import android.widget.BaseAdapter;
8 import android.widget.TextView;
9
10 import com.fightzhao.myadapter1.R;
11 import com.fightzhao.myadapter1.dao.Student;
12
13 import java.util.ArrayList;
14
15 /**
16 * Created by fightzhao on 15-9-16.
17 */
18 public class FirstAdapter extends BaseAdapter {
19 private ArrayList<Student> data;
20 private Context context;
21 // private Student chosenStudent;
22
23 public FirstAdapter(Context context, ArrayList<Student> data) {
24 this.context = context;
25 this.data = data == null ? new ArrayList<Student>() : data;
26 }
27
28 @Override
29 public int getCount() {
30 return data.size();
31 }
32
33 @Override
34 public Object getItem(int position) {
35 if (position > data.size())
36 return null;
37 return data.get(position);
38 }
39
40 @Override
41 public long getItemId(int position) {
42 return position;
43 }
44
45 @Override
46 public View getView(int position, View convertView, ViewGroup parent) {
47 ViewHolder holder;
48 if (null == convertView) {
49 convertView = LayoutInflater.from(context).inflate(R.layout.item_student, null);
50 holder = new ViewHolder();
51 holder.student_name = (TextView) convertView.findViewById(R.id.student_name);
52 holder.student_addr = (TextView) convertView.findViewById(R.id.student_addr);
53 convertView.setTag(holder);
54 } else {
55 holder = (ViewHolder) convertView.getTag();
56 }
57 holder.student_name.setText(data.get(position).getName());
58 holder.student_addr.setText(data.get(position).getAddr());
59 return convertView;
60 }
61
62 class ViewHolder {
63 TextView student_name;
64 TextView student_addr;
65 }
66 // public void setChosenStudent(Student student){
67 // chosenStudent = student;
68 // notifyDataSetChanged();
69 // }
70 // public Student getChosenStudent(){
71 // return chosenStudent;
72 // }
73 }
这里的Student就是以模拟数据,不贴代码了.
如果项目中用到的适配器不是很多的话,用这个是没问题的,但是,为了更好扩展的话,看来下张奇大大的做法,这里直接引用:
Android简便通用的SimpleBaseAdapter 链接:http://www.stormzhang.com/androidtips/2014/08/31/android-common-simplebaseadapter/
代码:
1 package com.fightzhao.myadapter1.ui.adapter;
2
3 import android.content.Context;
4 import android.util.SparseArray;
5 import android.view.View;
6 import android.view.ViewGroup;
7 import android.widget.BaseAdapter;
8
9 import java.util.ArrayList;
10 import java.util.List;
11
12 /**
13 * Created by fightzhao on 15-9-16.
14 */
15 public abstract class SimpleBaseAdapter<T> extends BaseAdapter {
16 protected Context context;
17 protected List<T> data;
18
19 public SimpleBaseAdapter(Context context, List<T> data) {
20 this.context = context;
21 this.data = data == null ? new ArrayList<T>() : new ArrayList<T>(data);
22 }
23
24 @Override
25 public int getCount() {
26 return data.size();
27 }
28
29 @Override
30 public Object getItem(int position) {
31 if (position >= data.size())
32 return null;
33 return data.get(position);
34 }
35
36 @Override
37 public long getItemId(int position) {
38 return position;
39 }
40
41 /**
42 * 该方法需要子类实现，需要返回item布局的resource id
43 *
44 * @return
45 */
46 public abstract int getItemResource();
47
48 /**
49 * 使用该getItemView方法替换原来的getView方法，需要子类实现
50 *
51 * @param position
52 * @param convertView
53 * @param holder
54 * @return
55 */
56 public abstract View getItemView(int position, View convertView, ViewHolder holder);
57
58 @SuppressWarnings("unchecked")
59 @Override
60 public View getView(int position, View convertView, ViewGroup parent) {
61 ViewHolder holder;
62 if (null == convertView) {
63 convertView = View.inflate(context, getItemResource(), null);
64 holder = new ViewHolder(convertView);
65 convertView.setTag(holder);
66 } else {
67 holder = (ViewHolder) convertView.getTag();
68 }
69 return getItemView(position, convertView, holder);
70 }
71
72 public class ViewHolder {
73 private SparseArray<View> views = new SparseArray<View>();
74 private View convertView;
75 public ViewHolder(View convertView) {
76 this.convertView = convertView;
77 }
78 /**
79 * 通过控件的Id获取对应的控件，如果没有则加入views
80 *
81 * @param resId
82 * @param <T>
83 * @return
84 */
85 @SuppressWarnings("unchecked")
86 public <T extends View> T getView(int resId) {
87 View v = views.get(resId);
88 if (null == v) {
89 v = convertView.findViewById(resId);
90 views.put(resId, v);
91 }
92 return (T) v;
93 }
94 }
95
96 public void add(T t) {
97 data.add(t);
98 notifyDataSetChanged();
99 }
100
101 public void addAll(List<T> elem) {
102 data.addAll(elem);
103 notifyDataSetChanged();
104 }
105
106 public void remove(T elem) {
107 data.remove(elem);
108 notifyDataSetChanged();
109 }
110
111 public void remove(int index) {
112 data.remove(index);
113 notifyDataSetChanged();
114 }
115
116 public void replaceAll(List<T> elem) {
117 data.clear();
118 data.addAll(elem);
119 notifyDataSetChanged();
120 }
121 }
使用:
1 package com.fightzhao.myadapter1.ui.adapter;
2
3 import android.content.Context;
4 import android.view.View;
5 import android.widget.TextView;
6
7 import com.fightzhao.myadapter1.R;
8 import com.fightzhao.myadapter1.dao.Student;
9
10 import java.util.List;
11
12 /**
13 * Created by fightzhao on 15-9-16.
14 */
15 public class SecoundAdapter extends SimpleBaseAdapter<Student> {
16 public SecoundAdapter(Context context, List<Student> data) {
17 super(context, data);
18 }
19 @Override
20 public int getItemResource() {
21 return R.layout.item_student;
22 }
23 @Override
24 public View getItemView(int position, View convertView, ViewHolder holder) {
25 TextView student_name = holder.getView(R.id.student_name);
26 TextView student_addr = holder.getView(R.id.student_addr);
27 student_name.setText(data.get(position).getName());
28 student_addr.setText(data.get(position).getAddr());
29 return convertView;
30 }
31 }
之后在MainActivity中使用即可:
1 package com.fightzhao.myadapter1;
2
3 import android.app.Activity;
4 import android.os.Bundle;
5 import android.view.View;
6 import android.widget.AdapterView;
7 import android.widget.ListView;
8 import android.widget.Toast;
9
10 import com.fightzhao.myadapter1.dao.Student;
11 import com.fightzhao.myadapter1.ui.adapter.FirstAdapter;
12 import com.fightzhao.myadapter1.ui.adapter.SecoundAdapter;
13
14 import java.util.ArrayList;
15
16 public class MainActivity extends Activity {
17 private ListView listView;
18 private ArrayList<Student> data;
19 private FirstAdapter firstAdapter;
20 SecoundAdapter secoundAdapter;
21
22 @Override
23 protected void onCreate(Bundle savedInstanceState) {
24 super.onCreate(savedInstanceState);
25 setContentView(R.layout.activity_main);
26 initView();
27 initData();
28 // firstAdapter = new FirstAdapter(this,data);
29 // listView.setAdapter(firstAdapter);
30 secoundAdapter =new SecoundAdapter(this,data);
31 listView.setAdapter(secoundAdapter);
32
33 }
34
35
36 private void initView() {
37 listView = (ListView) findViewById(R.id.listview);
38 listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
39 @Override
40 public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
41 Student student = (Student) parent.getItemAtPosition(position);
42 // firstAdapter.setChosenStudent(student);
43 if(view.hasFocusable()){
44 view.setBackgroundResource(R.color.item_pink);
45 }
46
47 Toast.makeText(getApplicationContext(),"sad",Toast.LENGTH_SHORT).show();
48 }
49 });
50
51 }
52
53
54
55
56
57 private void initData() {
58 data = new ArrayList<>();
59 data.add(new Student("张三", "北京"));
60 data.add(new Student("张学友", "香港"));
61 data.add(new Student("周杰伦", "台湾"));
62 data.add(new Student("梁朝伟", "香港"));
63 data.add(new Student("李四", "合肥"));
64
65
66 }
67
68 }
时间： 2024-10-09 20:16:36