Android-Adapter实现方法(ArrayAdapter,SimpleAdapter,SimpleCursorAdapter)

Adapter

总结

Adapter常用的实现类包括ArrayAdapter、SimpleAdapter、SimpleCursorAdapter、BaseAdapter。Adapter可以实现数据先加载再动态显示在界面上，而不是固定死界面有多少个列表（类似于web开发中的动态网页），是一个非常重要的内容。

Adapter　常用实现类：

类型 描述 ArrayAdapter 将数组或List集合的多个值包装成多个列表项 SimpleAdapter 将List集合的多个对象包装成多个列表项 SimpleCursorAdapter 包装Cursor提供的数据 BaseAdapter 可对各列表项进行最大限度地定制

ArrayAdapter（基于ListActivity）

使用简单，但是只能实现文本内容(TextView)

package com.example.huaro.proj_09;import android.app.ListActivity;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.widget.ArrayAdapter;public class MainActivity extends ListActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        String[] arr=new String[]{                "猪八戒",                "何洪达",                "萌萌哒"        };        ArrayAdapter<String> arrayAdapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_multiple_choice,arr);        setListAdapter(arrayAdapter);    }}

SimpleAdapter (图片和文字)

并不简单，功能强大，大部分的列表实现均可使用SimpleAdapter

<!--main界面代码，定义一个ListView--><?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="horizontal"    android:layout_width="match_parent"    android:layout_height="wrap_content">    <ListView        android:id="@+id/mylist"        android:layout_width="match_parent"        android:layout_height="wrap_content"/></LinearLayout>

<!--simple_item界面代码 嵌入main界面中的ListView--><?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="horizontal"    android:layout_width="match_parent"    android:layout_height="wrap_content"><ImageView    android:id="@+id/header"    android:layout_width="wrap_content"    android:layout_height="wrap_content"/>    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="vertical">        <TextView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:id="@+id/name"/>        <TextView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:textSize="14sp"            android:id="@+id/desc"/>    </LinearLayout></LinearLayout>

//Activity代码package com.example.huaro.proj_09;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.widget.AdapterView;import android.widget.ListView;import android.widget.SimpleAdapter;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;/** * Created by HUARO on 2016/2/10 0010. */public class Test extends Activity{    //位于/res/drawable下的三张图片    private int[] images=new int[]{            R.drawable.img_08,            R.drawable.img_08,            R.drawable.img_08    };    //数据    private String[] names=new String[]{            "你好",            "萌萌哒",            "呵呵大"    };    //数据    private String[] descs=new String[]{            "我就是我不一样的烟火",            "你就是你",            "哈哈"    };    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        //加载界面        setContentView(R.layout.main);        //定义List集合        List<Map<String,Object>> listmap=new ArrayList<Map<String,Object>>();        //List集合添加数据        for (int i=0;i<names.length;i++){            Map<String,Object> listItem=new HashMap<String,Object>();            listItem.put("header",images[i]);            listItem.put("personName",names[i]);            listItem.put("desc",descs[i]);            listmap.add(listItem);        }        /*         *创建一个simpleListView         *参数（context,List,view,String[]{"list中的各项参数"},int[]{"对应显示界面的id"}）        */        SimpleAdapter simpleAdapter=new SimpleAdapter(this,listmap,R.layout.simple_item,new String[]{"personName","header","desc"},new int[]{R.id.name,R.id.header,R.id.desc});        //获取界面ListView        ListView list=(ListView)findViewById(R.id.mylist);        //为ListView设置Adapter        list.setAdapter(simpleAdapter);        //为ListView的列表项绑定点击事件        list.setOnItemClickListener(new AdapterView.OnItemClickListener() {            @Override            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {            //Toast提示消息            Toast.makeText(MainActivity.this, "数据"+names[position]+":"+descs[position], Toast.LENGTH_SHORT).show();            }        });        list.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {            @Override            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {                //Toast提示消息            Toast.makeText(MainActivity.this, "数据"+names[position]+":"+descs[position], Toast.LENGTH_SHORT).show();            }            @Override            public void onNothingSelected(AdapterView<?> parent) {            }        });    }}

SimpleCursorAdapter(SQLite数据库)

<!--两个文本框，一个按钮，用作数据插入数据库--><?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.example.huaro.proj_data_sqlite.MainActivity">    <EditText        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:textAppearance="?android:attr/textAppearanceLarge"        android:text="Large Text"        android:id="@+id/edit1"        android:layout_alignParentTop="true"        android:layout_centerHorizontal="true" />    <EditText        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:textAppearance="?android:attr/textAppearanceLarge"        android:text="Large Text"        android:id="@+id/edit2"        android:layout_below="@+id/edit1"        android:layout_centerHorizontal="true" />    <Button        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="插入"        android:id="@+id/button"        android:layout_below="@+id/edit2"        android:layout_centerHorizontal="true"        android:layout_marginTop="45dp"        android:onClick="insertSQL"/>    <ListView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:id="@+id/show"        android:layout_below="@+id/button"        android:layout_centerHorizontal="true" /></RelativeLayout>

<!--用作显示数据库内容--><?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical" android:layout_width="match_parent"    android:layout_height="match_parent"    android:weightSum="1">    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:textAppearance="?android:attr/textAppearanceLarge"        android:text="Large Text"        android:id="@+id/my_title"        android:layout_weight="0.03" />    <TextView        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="New Text"        android:id="@+id/my_content"        android:layout_weight="0.06" /></LinearLayout>

package com.example.huaro.proj_data_sqlite;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.CursorAdapter;import android.widget.EditText;import android.widget.ListView;import android.widget.SimpleCursorAdapter;public class MainActivity extends AppCompatActivity {    SQLiteDatabase sqLiteDatabase;    ListView listView;    Button button;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        sqLiteDatabase=SQLiteDatabase.openOrCreateDatabase(this.getFilesDir().toString()+"my.db3",null);        listView=(ListView)findViewById(R.id.show);    }    public void insertSQL(View view){        String title=((EditText)findViewById(R.id.edit1)).getText().toString();        String content=((EditText)findViewById(R.id.edit2)).getText().toString();        try{            insertData(sqLiteDatabase,title,content);            Cursor cursor=sqLiteDatabase.rawQuery("select *from news_inf",null);            inflateList(cursor);        }catch (Exception e){            //执行ddl创建数据表            sqLiteDatabase.execSQL("create table news_inf(_id integer"+" primary key autoincrement,"+" news_title varchar(50),"+" news_content varchar(255))");            //执行insert语句插入数据            insertData(sqLiteDatabase,title,content);            //执行查询            Cursor cursor=sqLiteDatabase.rawQuery("select *from news_inf",null);            inflateList(cursor);        }    }    private void insertData(SQLiteDatabase db,String title,String content){        //执行插入语句        db.execSQL("insert into news_inf values(null,?,?)",new String[]{title,content});    }    private void inflateList(Cursor cursor){        //填充SimpleCursorAdapter        SimpleCursorAdapter simpleCursorAdapter=new SimpleCursorAdapter(MainActivity.this,R.layout.line,cursor,new String[]{"news_title","news_content"},new int[]{R.id.my_title,R.id.my_content}, CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);        //显示数据        listView.setAdapter(simpleCursorAdapter);    }    @Override    protected void onDestroy() {        super.onDestroy();        //退出程序时关闭SQLiteDatabase        if(sqLiteDatabase!=null&&sqLiteDatabase.isOpen()){            sqLiteDatabase.close();        }    }}

do a small fish in the sea;