Android 增删改查

针对数据库进行操作的文件，涵盖了对数据库进行增删改查的所有函数，select,updata,delete,insert

package com.example.stuapp.utils;

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

import androidx.annotation.Nullable;
import androidx.appcompat.app.AlertDialog;

import com.example.stuapp.MainActivity;
import com.example.stuapp.pojo.Stu;

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

public class StuHelp extends SQLiteOpenHelper {
private static StuHelp stuHelp;
private static final String Name="stu";

public static StuHelp getStuHelp(Context context) {if(stuHelp==null) stuHelp=new StuHelp(context);return stuHelp;
}
public long add(SQLiteDatabase sqLiteDatabase, Stu stu){System.out.println(stu.toString());ContentValues values=new ContentValues();values.put("id",stu.getId());values.put("name",stu.getName());values.put("age",stu.getAge());values.put("sex",stu.getSex());return sqLiteDatabase.insert(Name,null,values);
}

public long delete(SQLiteDatabase sqLiteDatabase,String id){
return sqLiteDatabase.delete(Name,"id=?",new String[]{id});
}
public long update(SQLiteDatabase sqLiteDatabase,Stu stu,String id){
ContentValues values=new ContentValues();
if(stu.getId()!=null&&!stu.getId().equals(""))
values.put("id",stu.getId());
if(stu.getName()!=null&&!stu.getName().equals(""))
values.put("name",stu.getName());
if(stu.getAge()!=null&&!stu.getAge().equals(""))
values.put("age",stu.getAge());
if(stu.getSex()!=null&&!stu.getSex().equals(""))
values.put("sex",stu.getSex());

    return sqLiteDatabase.update(Name,values,"id=?",new String[]{id});

}
public Stu select(SQLiteDatabase sqLiteDatabase,String id){
Cursor cursor=sqLiteDatabase.rawQuery("select * from stu where id=?",new String[]{id});
Stu stu=null;
if(cursor.getCount()>0){ cursor.moveToNext();stu=new Stu(cursor.getString(0),cursor.getString(1),cursor.getString(2),cursor.getString(3));}
return stu;
}
public List browse(SQLiteDatabase sqLiteDatabase){
List stus=new ArrayList<>();
Cursor cursor =sqLiteDatabase.query(Name,null,null,null,null,null,null);
while (cursor.moveToNext()){
Stu stu=new Stu();
stu.setId(cursor.getString(0));
stu.setName(cursor.getString(1));
stu.setAge(cursor.getString(2));
stu.setSex(cursor.getString(3));
stus.add(stu);
}
return stus;
}
private StuHelp(@Nullable Context context) {
super(context,Name ,null, 1);
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
String sql="create table if not exists stu(" +
"id varchar(10) not null primary key," +
"name varchar(10) not null," +
"age varchar(10) not null," +
"sex varchar(10) not null)";
sqLiteDatabase.execSQL(sql);
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

}

接下来要针对增删改查各个操作的页面编写其对应的activity文件