AndriodStudio期中利用ListView和数据库实现简单学生管理

数据库的创建

package com.example.myapp;

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

public class DbHelper extends SQLiteOpenHelper {
    final String create_table="CREATE TABLE Student (_id integer primary key autoincrement,xm text,xh text,bj text,zy text,cj text)";
    final String create_register="CREATE TABLE Register (_id integer primary key autoincrement,xm text,xh text)";
//创建两张表，一张student，一张register表
    Context context;
    public DbHelper(Context context,String dbname,int version){
        super(context,dbname,null,version);
        this.context=context;//上下文
    }
    @Override
    public void onCreate(SQLiteDatabase db) {db.execSQL(create_table); db.execSQL(create_register);}

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("drop table if exists Student");
        db.execSQL("drop table if exists Register");
        db.execSQL(create_table);
        db.execSQL(create_register);
//完成创建
    }
// 对表进行数据的插入方法
    public void insert(String tableName, ContentValues values){
        SQLiteDatabase db = getReadableDatabase();
        db.insert(tableName,null,values);
        Toast.makeText(context,"成功插入数据！",Toast.LENGTH_SHORT).show();
    }
//查询表中所有
    public Cursor queryAll(String tableName){
        SQLiteDatabase db = getReadableDatabase();
        Cursor cursor = db.query(tableName,null,null,null,null,null,null);
        return cursor;
    }
//对表中的姓名和学号进行单独的查询
    public Boolean queryByStudentXhAndXm(String tableName,String xm,String xh){
        SQLiteDatabase db = getReadableDatabase();
        Cursor cursor = db.query(tableName,new String[]{"xm,xh"},"xm=? and xh=?",new String[]{xm,xh},null,null,null);
        if (cursor.moveToFirst()) {
            return true;
        }else {
            return false;
        }
    }
//删除表中数据的方法
    public void delStudent(String id){
        SQLiteDatabase db = getWritableDatabase();
        db.delete("Student","_id=?",new String[]{id});
    }
//对表进行更新
    public void  updateStudent(String id,ContentValues values){
        SQLiteDatabase db = getWritableDatabase();
        db.update("Student",values,"_id=?",new String[]{id});
    }
}

创建了两张表格，一张用来储存学生信息，Student表：id(主键)，姓名，学号，班级，专业，成绩。

一张register表：id(主键)，姓名，学号。用来储存登录信息

其余类和其布局文件

MainActivity.class(登录界面)

package com.example.myapp;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    EditText et1,et2;
    Button btn1,btn2;
    DbHelper dbHelper;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        dbHelper=new DbHelper(MainActivity.this,"MyDataBase,",3);
        setContentView(R.layout.activity_main);
        et1=findViewById(R.id.et1);
        et2=findViewById(R.id.et2);
        btn1=findViewById(R.id.dl);
        btn2=findViewById(R.id.zc);

        btn1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String xm=et1.getText().toString();
                String xh=et2.getText().toString();
                if (xm.isEmpty()||xh.isEmpty()){
                    Toast.makeText(MainActivity.this,"姓名或者学号不可为空",Toast.LENGTH_SHORT).show();
                }
                if (dbHelper.queryByStudentXhAndXm("Register",xm,xh)){
                    Intent intent=new Intent(MainActivity.this,Manage.class);
                    startActivity(intent);
                }
            }
        });
        btn2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent=new Intent(MainActivity.this,Register.class);
                startActivity(intent);
            }
        });
    }
}

activity_main.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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+