一、ListView介紹
ListView是類似於將一個介面分為一行一行,如:
ListView只是一個視圖,而如果要在這個列表視圖中顯示資料,則必須要通過“Adapter”,我們通常有三種Adapter:
(1)ArrayAdapter:每行只能是一個文本;
(2)SimpleAdapter:此種方式不是很好,經過測試,只能顯示一行資料;
(3)繼承BaseAdapter:此種方式較靈活,可以自訂將每行對應到不同的布局xml中;
(4)SimpleCursorAdapter:此處傳入的資料不是List,而是資料庫查詢返回的Cursor;
二、ListView執行個體
這個執行個體分別實現了三種ListView的使用;
工程的階層如下:
ListView的介面:
ArrayAdapter的顯示介面如下:
SimpleAdapter的介面如下:
ExtendBaseAdapter的介面如下:
1.主介面模組:
ListViewActivity.java
package org.xiazdong;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.ArrayAdapter;import android.widget.Button;public class ListViewActivity extends Activity implements OnClickListener{private Button btn1;private Button btn2;private Button btn3; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main);//一定要先setContentView,才findViewById btn1 = (Button) this.findViewById(R.id.arrayAdapter); btn2 = (Button) this.findViewById(R.id.simpleAdapter); btn3 = (Button)this.findViewById(R.id.baseAdapter); btn1.setOnClickListener(this); btn2.setOnClickListener(this); btn3.setOnClickListener(this); }@Overridepublic void onClick(View v) {if(v==btn1){Intent intent = new Intent(ListViewActivity.this,ArrayAdapterActivity.class);this.startActivity(intent);}else if(v==btn2){Intent intent = new Intent(ListViewActivity.this,SimpleAdapterActivity.class);this.startActivity(intent);}else if(v==btn3){Intent intent = new Intent(ListViewActivity.this,ExtendBaseAdapterActivity.class);this.startActivity(intent);}}}
main.xml
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <TextView android:id="@+id/tv" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:text="ListView的使用" android:textSize="50px" /> <Button android:id="@+id/arrayAdapter" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_below="@id/tv" android:text="ArrayAdapter" > </Button> <Button android:id="@+id/simpleAdapter" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_below="@id/arrayAdapter" android:text="SimpleAdapter" > </Button><Button android:id="@+id/baseAdapter" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_below="@id/simpleAdapter" android:text="ExtendBaseAdapter" > </Button> <TextView android:id="@+id/textView1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_alignParentRight="true" android:layout_marginBottom="142dp" android:layout_marginRight="16dp" android:text="by xiazdong" android:textSize="20px" /></RelativeLayout>
2.ArrayAdapter模組
ArrayAdapterActivity.java
package org.xiazdong;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.os.Bundle;import android.widget.ArrayAdapter;import android.widget.ListView;/* * 每建立一個Activity就要在AndroidManifest.xml中聲明 * ArrayAdapter只能顯示基本的字串 * SimpleAdapter能夠顯示自訂視圖 */public class ArrayAdapterActivity extends Activity {private ListView lv;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);lv = new ListView(this); //ListView繼承ViewList<String> list = new ArrayList<String>();for (int i = 0; i < 10; i++) {list.add("xiazdong-" + i);}ArrayAdapter<String> sa = new ArrayAdapter<String>(this, //將List賦給ArrayAdapter,採用simple_item_1樣式android.R.layout.simple_list_item_1, list);lv.setAdapter(sa);//將ArrayAdapter的值對應到ListView中this.setContentView(lv);}}
3.SimpleAdapter模組
一般ListView都是用來顯示列表的,一般列表的資料都是來自資料庫的,因此我們這裡假設前面已經實現了一個DBService類,裡面存在pageQuery(int offset,int length);
比如dbservice.pageQuery(3,5);表示跳過3個記錄,插入5條記錄;
main.xml
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <LinearLayout android:layout_width="wrap_content"//注意一定要wrap_content android:layout_height="wrap_content"//注意一定要wrap_content android:orientation="horizontal" > <TextView android:layout_width="100dp" android:layout_height="wrap_content" android:text="ID" /> <TextView android:layout_width="100dp" android:layout_height="wrap_content" android:text="NAME" /> <TextView android:layout_width="100dp" android:layout_height="wrap_content" android:text="AGE" /> </LinearLayout> <ListView android:id="@+id/listview" android:layout_width="wrap_content" android:layout_height="fill_parent" > </ListView></LinearLayout>
item.xml
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="horizontal" > <TextView android:id="@+id/id1" android:layout_width="100dp" android:layout_height="wrap_content" /> <TextView android:id="@+id/name" android:layout_width="100dp" android:layout_height="wrap_content" /> <TextView android:id="@+id/age" android:layout_width="100dp" android:layout_height="wrap_content" /></LinearLayout>
MainActivity.java
package org.xiazdong.db;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import org.xiazdong.db.domain.Person;import org.xiazdong.db.service.DBService;import android.app.Activity;import android.os.Bundle;import android.util.Log;import android.widget.ListView;import android.widget.SimpleAdapter;public class MainActivity extends Activity {private ListView listView;@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); listView = (ListView)this.findViewById(R.id.listview); DBService service = new DBService(this); List<Person> persons = service.pageQuery(0, 10); List<HashMap<String,Object>> data = new ArrayList<HashMap<String,Object>>(); for(Person person:persons){ HashMap<String,Object>map = new HashMap<String,Object>(); map.put("id", person.getId()); map.put("name", person.getName()); map.put("age", person.getAge()); data.add(map); } System.out.println(data); SimpleAdapter adapter = new SimpleAdapter(this, data, R.layout.item, new String[]{"id","name","age"}, new int[]{R.id.id1,R.id.name,R.id.age});//data表示顯示的資料,一個Map為一行,List<Map>表示多行//R.layout.item表示一個item的布局//new String[]{"id","name","age"}表示將key="id"的值對應到R.id.id1上 listView.setAdapter(adapter);}}
總結:SimpleAdapter不需要內部實現Adapter,只能實現每個item布局都一樣的列表;
4.繼承BaseAdapter類
ExtendBaseAdapterActivity.java
package org.xiazdong;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.os.Bundle;import android.widget.ArrayAdapter;import android.widget.ListView;public class ExtendBaseAdapterActivity extends Activity {private ListView lv;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);lv = new ListView(this);MyAdapter ma = new MyAdapter(this, new int[] { R.layout.sub1,R.layout.sub2 }); // 分別在每行中顯示sub1的布局和sub2的布局lv.setAdapter(ma);this.setContentView(lv);}}
MyAdapter.java
package org.xiazdong;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.View.OnClickListener;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.Button;import android.widget.CheckBox;import android.widget.CompoundButton;import android.widget.CompoundButton.OnCheckedChangeListener;import android.widget.Toast;public class MyAdapter extends BaseAdapter {private Context context;private int layoutID[];private LayoutInflater inflator;public MyAdapter(Context context, int layoutID[]) {this.context = context;this.layoutID = layoutID;inflator = LayoutInflater.from(context);}@Overridepublic int getCount() { // 一個布局佔一行return layoutID.length;}@Overridepublic Object getItem(int position) {return null;}@Overridepublic long getItemId(int position) {return 0;}@Override// position表示要顯示第幾行,0表示第一行// convertView表示要顯示的視圖public View getView(int position, View convertView, ViewGroup parent) {convertView = inflator.inflate(layoutID[position], null);//每次將一個布局xml映射到一項中if (convertView.findViewById(R.id.checkBox1) instanceof CheckBox) {CheckBox cb1 = (CheckBox) convertView.findViewById(R.id.checkBox1);cb1.setOnCheckedChangeListener(new OnCheckedChangeListener() {@Overridepublic void onCheckedChanged(CompoundButton buttonView,boolean isChecked) {Toast t = Toast.makeText(context, "點擊了複選框", Toast.LENGTH_SHORT);t.show();}});}if (convertView.findViewById(R.id.button1) instanceof Button) {Button b1 = (Button) convertView.findViewById(R.id.button1);b1.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {Toast t = Toast.makeText(context, "點擊了按鈕", Toast.LENGTH_SHORT);t.show();}});}return convertView;}}
sub1.xml
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" > <TextView android:id="@+id/textView1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignBaseline="@+id/checkBox1" android:layout_alignBottom="@+id/checkBox1" android:layout_alignParentLeft="true" android:text="點擊彈出提示" /> <CheckBox android:id="@+id/checkBox1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentRight="true" android:layout_alignParentTop="true" android:text="" /> </RelativeLayout>
sub2.xml
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" > <TextView android:id="@+id/textView2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignBaseline="@+id/button1" android:layout_alignBottom="@+id/button1" android:layout_alignParentLeft="true" android:text="TextView" /><Button android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentRight="true" android:layout_alignParentTop="true" android:text="Button" /></RelativeLayout>
5.SimpleCursorAdapter
注意:如果要使用SimpleCursorAdapter,則要求Cursor的結果集的主鍵名為_id,因此我們在查詢時要用 as _id 進行別名;
比如select id,name from person; 現在要用 select id as _id,name from person; 即可;
主要步驟:
Cursor cursor = query();
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, /*Cotnext*/
R.layout.item, /*一個item的布局*/
cursor,
new String[]{"name","age"}, /*name,age分別為資料庫中表的屬性*/
new int[]{R.id.name,R.id.age});/*R.id.name,R.id.age可以顯示資料*/
listview.setAdapter(adapter);
總結:
ListView的應用有很多,比如
(1)在一般的遊戲中列出熱門排行榜;
(2)“設定”中列出多種子設定;
(3)字典列出單詞;
(4)通訊錄列表;