android学习散记—数据库与listview的结合

主要思路：通过键盘输入EditText并储蓄到数据库中，通过listview与数据库进行绑定，并显示在屏幕上。

1，布局文件

ⅠMainActivty

<?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: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.sayoulala.mydb_example.MainActivity"
android:orientation="vertical">


<EditText
android:id="@+id/name"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<EditText
android:id="@+id/title"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<Button
android:id="@+id/add"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="add"/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<ListView
android:id="@+id/list_item"
android:layout_width="match_parent"
android:layout_height="wrap_content">

</ListView>
</LinearLayout>
</LinearLayout>

Ⅱ.listview的布局文件（两个textview显示数据）

<?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="vertical">
    <TextView
        android:id="@+id/new_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/new_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

源代码

ackage com.example.sayoulala.mydb_example;

import android.content.DialogInterface;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MainActivity extends AppCompatActivity {
    private MyDb myDb;
    private ListView listView;
    private EditText editTextname;
    private EditText editTexttitle;
    private Button add;
    private List<Map<String,Object>> list;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        editTextname=(EditText)findViewById(R.id.name);
        editTexttitle=(EditText)findViewById(R.id.title);
        listView=(ListView)findViewById(R.id.list_item);
        add=(Button)findViewById(R.id.add);
        myDb=new MyDb(this);

        add.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db=myDb.getReadableDatabase();
                String name=editTextname.getText().toString();//获取输入的字符
                String title=editTexttitle.getText().toString();//获取输入的字符
                db.execSQL("insert into example(name,title)values(?,?)", new String[]{name, title});//将数据传入到数据库

                /*Cursor c=db.rawQuery("select * from example",null);
                SimpleAdapter simpleAdapter=new SimpleAdapter( MainActivity.this,add(c),R.layout.list_layout,new String[]{"name","title"},
                        new int[]{R.id.new_name,R.id.new_title});
                listView.setAdapter(simpleAdapter);/*用simpleAdapter绑定数据到listview上
                editTextname.setText("");
                editTexttitle.setText("");
            }
        });
     listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {//删除数据操作
         @Override
         public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
             final int n=position;
             final AlertDialog.Builder builder=new AlertDialog.Builder(MainActivity.this);
             builder.setTitle("删除该数据" );
             builder.setMessage("确定删除吗？" );
             builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
                 @Override
                 public void onClick(DialogInterface dialog, int which) {
                     HashMap<String,String> map=(HashMap<String,String>)listView.getItemAtPosition(n);
                     String name=map.get("name");
                     String title=map.get("title");
                     SQLiteDatabase db=myDb.getReadableDatabase();
                     db.delete("example","name=?",new String[]{name});
                     Cursor c=db.rawQuery("select * from example",null);
                     SimpleAdapter simpleAdapter=new SimpleAdapter( MainActivity.this,add(c),R.layout.list_layout,new String[]{"name","title"},
                             new int[]{R.id.new_name,R.id.new_title});
                     listView.setAdapter(simpleAdapter);
                 }
             });
             builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
                 @Override
                 public void onClick(DialogInterface dialog, int which) {

                 }
             });
             builder.create();
             builder.show();
         }
     });
    }
    private List<Map<String, Object>> add(Cursor cursor)//绑定数据
    {

        List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
        if(cursor.moveToLast())
        {
                do {


                Map<String, Object> map = new HashMap<String, Object>();
                map.put("name",cursor.getString(cursor.getColumnIndex("name")));
                map.put("title",cursor.getString(cursor.getColumnIndex("title")));
                list.add(map);

            }while (cursor.moveToPrevious());
        }

        return list;
    }


}