listview小例子

其他 2018-06-14 12:07:35 阅读次数: 2

编写一个从数据库里查询数据展示到listview上的案例

运行结果：点击find按钮，会将数据库中添加的数据显示在List View上



结果如下：


创建如图所示：




代码如下：

PersonAdapter



package cn.edu.bzu.datashow.adapter;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

import java.util.List;

import cn.edu.bzu.datashow.R;
import cn.edu.bzu.datashow.entity.Person;
public class PersonAdapter extends ArrayAdapter<Person> {
   private int resourceId;
   public PersonAdapter(Context context, int textViewResourceId,
                   List<Person> objects) {
      super(context, textViewResourceId, objects);
      resourceId = textViewResourceId;
   }
   @Override
   public View getView(int position, View convertView, ViewGroup parent) {
      Person person= getItem(position);
      View view;
      ViewHolder viewHolder;
      if (convertView == null) {
         //任务 补充完整
         view = LayoutInflater.from(getContext()).inflate(resourceId, null);
         viewHolder = new ViewHolder();
         viewHolder.tvName = (TextView) view.findViewById(R.id.tvName);
         viewHolder.tvPhone = (TextView) view.findViewById(R.id.tvPhone);
         view.setTag(viewHolder);
      } else {
         view = convertView;
         viewHolder = (ViewHolder) view.getTag();
      }
      viewHolder.tvName.setText(person.getName());
      viewHolder.tvPhone.setText(person.getPhone());
      return view;
   }

   class ViewHolder {
      TextView tvName;
      TextView tvPhone;

   }
}

PersonDao:



package cn.edu.bzu.datashow.dao;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

import java.util.ArrayList;
import java.util.List;

import cn.edu.bzu.datashow.db.PersonDBHelper;
import cn.edu.bzu.datashow.entity.Person;
/**
 * Created by fengj on 2017/5/10.
 */
public class PersonDao {
    private PersonDBHelper personDBHelper;
    public PersonDao(Context context){
        personDBHelper=new PersonDBHelper(context);
    }
    public void add(Person person){
        SQLiteDatabase sqLiteDatabase=personDBHelper.getWritableDatabase();
        ContentValues contentValues=new ContentValues();
        contentValues.put("name",person.getName());
        contentValues.put("phone",person.getPhone());
        sqLiteDatabase.insert("info",null,contentValues);
    }
    public List<Person> getPersons(){
        //任务 完成查询所有数据的方法
        List<Person> persons=new ArrayList<Person>();
        SQLiteDatabase sqLiteDatabase=personDBHelper.getWritableDatabase();
        Cursor cursor=sqLiteDatabase.query("info",null,null,null,null,null,null);
        while(cursor.moveToNext()){
           int id= cursor.getInt(cursor.getColumnIndex("_id"));
            String name=cursor.getString(cursor.getColumnIndex("name"));
            String phone=cursor.getString(cursor.getColumnIndex("phone"));
            Person person=new Person(name,phone);
            person.setId(id);
            persons.add(person);
        }
        return persons;
    }
}
 
PersonDBHelper: 


package cn.edu.bzu.datashow.db;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

/**
 * Created by fengj on 2017/5/10.
 */
//任务：修正问题
public class PersonDBHelper extends SQLiteOpenHelper {
    //数据库的名称为person.db ,数据库的版本为1
    public PersonDBHelper(Context context) {
        super(context,"person.db", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table info(_id integer primary key,name varchar(20),phone varchar(20))");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}
 
MainActivity: 

package cn.edu.bzu.datashow;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ListView;

import java.util.List;

import cn.edu.bzu.datashow.adapter.PersonAdapter;
import cn.edu.bzu.datashow.dao.PersonDao;
import cn.edu.bzu.datashow.entity.Person;

public class MainActivity extends AppCompatActivity {
    private PersonDao personDao;
    private ListView lvPersons;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lvPersons= (ListView) findViewById(R.id.lvPersons);
        personDao=new PersonDao(this);
        personDao.add(new Person("张三","13476089006"));
        personDao.add(new Person("李四","13476089008"));
    }

    public void find(View view){
        //任务 查询数据库中的所有person，显示在列表中
        List<Person> persons=personDao.getPersons();
        PersonAdapter personAdapter=new PersonAdapter(this,R.layout.item,persons);
        lvPersons.setAdapter(personAdapter);


    }
}
Activity-main.xml: 


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    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"
    android:orientation="vertical"
    tools:context="cn.edu.bzu.datashow.MainActivity">

    <ListView
        android:id="@+id/lvPersons"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:divider="@color/colorPrimary"
        android:layout_weight="1"
       />

    <Button
        android:text="Find"
        android:layout_gravity="center_horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/lvPersons"
        android:onClick="find"
        android:id="@+id/btnFind" />
</LinearLayout>
 
item.xml: 


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_shop"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    >
    <TextView
        android:text="名字"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tvName"
        android:textSize="24sp"
        />

    <TextView
        android:text="电话"
        android:layout_marginTop="10dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="18sp"
        android:id="@+id/tvPhone"
       />
</LinearLayout>
运行出来就好啦！ 

                </div>

编写一个从数据库里查询数据展示到listview上的案例

运行结果：点击find按钮，会将数据库中添加的数据显示在List View上



结果如下：


创建如图所示：




代码如下：

PersonAdapter



package cn.edu.bzu.datashow.adapter;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

import java.util.List;

import cn.edu.bzu.datashow.R;
import cn.edu.bzu.datashow.entity.Person;
public class PersonAdapter extends ArrayAdapter<Person> {
   private int resourceId;
   public PersonAdapter(Context context, int textViewResourceId,
                   List<Person> objects) {
      super(context, textViewResourceId, objects);
      resourceId = textViewResourceId;
   }
   @Override
   public View getView(int position, View convertView, ViewGroup parent) {
      Person person= getItem(position);
      View view;
      ViewHolder viewHolder;
      if (convertView == null) {
         //任务 补充完整
         view = LayoutInflater.from(getContext()).inflate(resourceId, null);
         viewHolder = new ViewHolder();
         viewHolder.tvName = (TextView) view.findViewById(R.id.tvName);
         viewHolder.tvPhone = (TextView) view.findViewById(R.id.tvPhone);
         view.setTag(viewHolder);
      } else {
         view = convertView;
         viewHolder = (ViewHolder) view.getTag();
      }
      viewHolder.tvName.setText(person.getName());
      viewHolder.tvPhone.setText(person.getPhone());
      return view;
   }

   class ViewHolder {
      TextView tvName;
      TextView tvPhone;

   }
}

PersonDao:



package cn.edu.bzu.datashow.dao;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

import java.util.ArrayList;
import java.util.List;

import cn.edu.bzu.datashow.db.PersonDBHelper;
import cn.edu.bzu.datashow.entity.Person;
/**
 * Created by fengj on 2017/5/10.
 */
public class PersonDao {
    private PersonDBHelper personDBHelper;
    public PersonDao(Context context){
        personDBHelper=new PersonDBHelper(context);
    }
    public void add(Person person){
        SQLiteDatabase sqLiteDatabase=personDBHelper.getWritableDatabase();
        ContentValues contentValues=new ContentValues();
        contentValues.put("name",person.getName());
        contentValues.put("phone",person.getPhone());
        sqLiteDatabase.insert("info",null,contentValues);
    }
    public List<Person> getPersons(){
        //任务 完成查询所有数据的方法
        List<Person> persons=new ArrayList<Person>();
        SQLiteDatabase sqLiteDatabase=personDBHelper.getWritableDatabase();
        Cursor cursor=sqLiteDatabase.query("info",null,null,null,null,null,null);
        while(cursor.moveToNext()){
           int id= cursor.getInt(cursor.getColumnIndex("_id"));
            String name=cursor.getString(cursor.getColumnIndex("name"));
            String phone=cursor.getString(cursor.getColumnIndex("phone"));
            Person person=new Person(name,phone);
            person.setId(id);
            persons.add(person);
        }
        return persons;
    }
}
 
PersonDBHelper: 


package cn.edu.bzu.datashow.db;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

/**
 * Created by fengj on 2017/5/10.
 */
//任务：修正问题
public class PersonDBHelper extends SQLiteOpenHelper {
    //数据库的名称为person.db ,数据库的版本为1
    public PersonDBHelper(Context context) {
        super(context,"person.db", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table info(_id integer primary key,name varchar(20),phone varchar(20))");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}
 
MainActivity: 

package cn.edu.bzu.datashow;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ListView;

import java.util.List;

import cn.edu.bzu.datashow.adapter.PersonAdapter;
import cn.edu.bzu.datashow.dao.PersonDao;
import cn.edu.bzu.datashow.entity.Person;

public class MainActivity extends AppCompatActivity {
    private PersonDao personDao;
    private ListView lvPersons;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lvPersons= (ListView) findViewById(R.id.lvPersons);
        personDao=new PersonDao(this);
        personDao.add(new Person("张三","13476089006"));
        personDao.add(new Person("李四","13476089008"));
    }

    public void find(View view){
        //任务 查询数据库中的所有person，显示在列表中
        List<Person> persons=personDao.getPersons();
        PersonAdapter personAdapter=new PersonAdapter(this,R.layout.item,persons);
        lvPersons.setAdapter(personAdapter);


    }
}
Activity-main.xml: 


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    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"
    android:orientation="vertical"
    tools:context="cn.edu.bzu.datashow.MainActivity">

    <ListView
        android:id="@+id/lvPersons"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:divider="@color/colorPrimary"
        android:layout_weight="1"
       />

    <Button
        android:text="Find"
        android:layout_gravity="center_horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/lvPersons"
        android:onClick="find"
        android:id="@+id/btnFind" />
</LinearLayout>
 
item.xml: 


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_shop"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    >
    <TextView
        android:text="名字"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tvName"
        android:textSize="24sp"
        />

    <TextView
        android:text="电话"
        android:layout_marginTop="10dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="18sp"
        android:id="@+id/tvPhone"
       />
</LinearLayout>
运行出来就好啦！ 

                </div>

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