ListView理解
ListView是一種用來顯示多個可滑動項(Item)列表的ViewGroup
需要使用Adapter將集合數據和每一個Item所對應的佈局動態適配到ListView中顯示
顯示列表: listView.setAdapter(adapter)
更新列表:adapter.notifyDataSetChanged()
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ListView效果樣例
Adapter
集合數據爲List<String>或String[]
集合數據必須是List<Map<String,Object>>類型
集合數據可以是任意類型的集合List<Xxx>
集合數據是數據庫查詢結果集
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ListView+ ArrayAdapter
context: 上下文件對象, 一般爲Acivity對象
resource:Item的佈局文件標識
objects: 需要顯示的數據集合(Array或List)
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ListView+ SimpleAdapter
context: 上下文件對象, 一般爲Acivity對象
data: 需要顯示的數據集合
resource:Item佈局文件標識
from: map對象中的key的數組, 用於得到對應的value
to:Item佈局文件中的子view的id的數組
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ListView+ BaseAdapter
classMyBaseAdapterextends BaseAdapter{
@Override
public intgetCount() {
return0;
}
@Override
public Object getItem(int position) {
returnnull;
}
@Override
public long getItemId(int position) {
return0;
}
@Override
public View getView(int position,
ViewconvertView, ViewGroup parent) {
returnnull;
}
}
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package com.example.test08_listvieew;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class CopyOfMainActivity_Simple extends Activity {
private ListView lv_main;
private List<ShoppInfo> data;//商品信息數據源
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv_main=(ListView) findViewById(R.id.lv_main);
//準備集合數據
data=new ArrayList<ShoppInfo>();
data.add(new ShoppInfo(R.drawable.f1,"美食名稱--1","美食的內容---1"));
data.add(new ShoppInfo(R.drawable.f2,"美食名稱--2","美食的內容---2"));
data.add(new ShoppInfo(R.drawable.f3,"美食名稱--3","美食的內容---3"));
data.add(new ShoppInfo(R.drawable.f4,"美食名稱--4","美食的內容---4"));
data.add(new ShoppInfo(R.drawable.f5,"美食名稱--5","美食的內容---5"));
data.add(new ShoppInfo(R.drawable.f6,"美食名稱--6","美食的內容---6"));
data.add(new ShoppInfo(R.drawable.f7,"美食名稱--7","美食的內容---7"));
data.add(new ShoppInfo(R.drawable.f8,"美食名稱--8","美食的內容---8"));
data.add(new ShoppInfo(R.drawable.f9,"美食名稱--9","美食的內容---9"));
data.add(new ShoppInfo(R.drawable.f10,"美食名稱--10","美食的內容---10"));
//準備適配器對象 BaseAdatper
MyAdapter adapter = new MyAdapter();
//
lv_main.setAdapter(adapter);
}
package com.example.test08_listvieew;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
public class MainActivity_Array extends Activity {
private ListView lv_main;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv_main=(ListView) findViewById(R.id.lv_main);
//準備集合
List<Map<String, Object>> data = new ArrayList<Map<String,Object>>();
HashMap<String, Object> mp = new HashMap<String, Object>();
mp.put("icon", R.drawable.f1);
mp.put("name", "美食---1");
mp.put("content", "內容--1");
data.add(mp);
mp=new HashMap<String, Object>();
mp.put("icon", R.drawable.f2);
mp.put("name", "美食---2");
mp.put("content", "內容--2");
data.add(mp);
mp=new HashMap<String, Object>();
mp.put("icon", R.drawable.f3);
mp.put("name", "美食---3");
mp.put("content", "內容--3");
data.add(mp);
mp=new HashMap<String, Object>();
mp.put("icon",R.drawable.f4);
mp.put("name", "美食---4");
mp.put("content", "內容--4");
data.add(mp);
mp=new HashMap<String, Object>();
mp.put("icon", R.drawable.f5);
mp.put("name", "美食---5");
mp.put("content", "內容--5");
data.add(mp);
mp=new HashMap<String, Object>();
mp.put("icon", R.drawable.f6);
mp.put("name", "美食---6");
mp.put("content", "內容--6");
data.add(mp);
mp=new HashMap<String, Object>();
mp.put("icon", R.drawable.f7);
mp.put("name", "美食---7");
mp.put("content", "內容--7");
data.add(mp);
mp=new HashMap<String, Object>();
mp.put("icon", R.drawable.f8);
mp.put("name", "美食---8");
mp.put("content", "內容--8");
data.add(mp);
mp=new HashMap<String, Object>();
mp.put("icon", R.drawable.f9);
mp.put("name", "美食---9");
mp.put("content", "內容--9");
data.add(mp);
mp=new HashMap<String, Object>();
mp.put("icon", R.drawable.f10);
mp.put("name", "美食---10");
mp.put("content", "內容--10");
data.add(mp);
//map對象的key數組 ，用於得到對應的value
String[] from={"icon","name","content"};
//item佈局文件中的子View的id的數組
int[] to={R.id.iv_item_icon,R.id.iv_item_name,R.id.iv_item_content};
//準備SimpleAdapter對象
SimpleAdapter adapter = new SimpleAdapter(this, data, R.layout.item_simple_adapter, from, to);
//設置Adapter顯示列表
lv_main.setAdapter(adapter);
}
}
@Override//返回集合的總數
public int getCount() {
return data.size();
}
@Override//返回指定下標對應的數據對象
public Object getItem(int position) {
return data.get(position);
}
@Override//返回每個條目的id 下標
public long getItemId(int position) {
return position;
}
@Override//返回指定下標所對應(Item)的視圖對象
//position 下標 parent listView對象
//convertView 可複用Item的視圖對象 前n+1個爲null
public View getView(int position, View convertView, ViewGroup parent) {
ViewHodler holder=null;
//如果沒有複用
if (convertView==null) {
//加載條目（Item）佈局 得到視圖(View)對象
convertView= View.inflate(CopyOfMainActivity_Simple.this,
R.layout.item_simple_adapter, null);
holder=new ViewHodler();
holder.inv = (ImageView) convertView.findViewById(R.id.iv_item_icon);
holder.nametext = (TextView) convertView.findViewById(R.id.iv_item_name);
holder.inv2 = (TextView) convertView.findViewById(R.id.iv_item_content);
//將holder 保存在convertView上
convertView.setTag(holder);
}else{
//複用時 取出holder
holder=(ViewHodler) convertView.getTag();
}
//2. 得到當前行的對象
ShoppInfo shoppInfo = data.get(position);
//3.給ViewHolder對象的數據設置數據
holder.inv.setImageResource(shoppInfo.getIcon());
holder.nametext.setText(shoppInfo.getName());
holder.inv2.setText(shoppInfo.getContent());
return convertView;
}//視圖容器類
class ViewHodler{
public ImageView inv;
public TextView nametext;
public TextView inv2;
}
}
}
package com.example.test08_listvieew;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.ListView;
public class MainActivity extends Activity {
private ListView lv_main;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv_main=(ListView) findViewById(R.id.lv_main);
//準備集合
String[] data={"A","B","C","D","E","F","G","H","J","K","L","O"};
//準備適配器ArrayAdapter對象
ArrayAdapter<String> adapter=new ArrayAdapter<String>
(this, R.layout.item_array,data);
//設置adapter顯示列表
lv_main.setAdapter(adapter);
}
}
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<ImageView
android:id="@+id/iv_icon"
android:layout_width="70dp"
android:layout_height="70dp"
android:src="@drawable/ic_launcher" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="70dp"
android:gravity="center_vertical"
android:orientation="vertical"
android:layout_marginLeft="10dp"
>
<TextView
android:id="@+id/tv_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView" />
<TextView
android:id="@+id/tv_content"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView" />
</LinearLayout>
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<ImageView
android:id="@+id/iv_item_icon"
android:layout_width="70dp"
android:layout_height="70dp"
android:src="@drawable/f1" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="70dp"
android:orientation="vertical"
android:gravity="center_vertical"
android:layout_marginLeft="10dp"
>
<TextView
android:id="@+id/iv_item_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
/>
<TextView
android:id="@+id/iv_item_content"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView" />
</LinearLayout>
</LinearLayout>
package com.example.test08_listvieew;
public class ShoppInfo {
private int icon;
private String name;
private String content;
public ShoppInfo() {
super();
}
public ShoppInfo(int icon, String name, String content) {
super();
this.icon = icon;
this.name = name;
this.content = content;
}
public int getIcon() {
return icon;
}
public void setIcon(int icon) {
this.icon = icon;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
@Override
public String toString() {
return "ShoppInfo [icon=" + icon + ", name=" + name + ", content="
+ content + "]";
}
}