第一次个人作业-打卡app

package com.example.newclock;

import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import database.UserDBHelper;
import entity.User;
import org.w3c.dom.Text;

import java.util.List;

public class SQLiteHelperActivity extends AppCompatActivity implements View.OnClickListener {
    private EditText et_id;
    private EditText et_name;
    private EditText et_ph;
    private EditText et_class;
    private TextView tv_show;
    private UserDBHelper mHelper;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sqlite_helper);
        et_id=findViewById(R.id.et_id);
        et_name=findViewById(R.id.et_name);
        et_ph=findViewById(R.id.et_ph);
        et_class=findViewById(R.id.et_class);
        tv_show = findViewById(R.id.tv_show);
        findViewById(R.id.bt_register).setOnClickListener(this);
        findViewById(R.id.bt_delete).setOnClickListener(this);
        findViewById(R.id.bt_update).setOnClickListener(this);
        findViewById(R.id.bt_all).setOnClickListener(this);

    }
    protected void onStart() {
        super.onStart();
        mHelper=UserDBHelper.getInstance(this);
        mHelper.openWriteLink();
        mHelper.openReadLink();
    }

    @Override
    protected void onStop() {
        super.onStop();
        mHelper.closeLink();
    }
    @Override
    public void onClick(View view) {
        String Id=et_id.getText().toString();
        String Name=et_name.getText().toString();
        String Pn=et_ph.getText().toString();
        String Class=et_class.getText().toString();
        int a=1;
        User user=new User();
        switch (view.getId())
        {
            case R.id.bt_register:
                user.setId(Id);
                user.setName(Name);
                user.setPn(Pn);
                user.setCs(Class);
                if(Pn.length()!=11)
                {
                    Toast.makeText(this, "请输入正确的手机号", Toast.LENGTH_SHORT).show();
                    return;
                }
                if(mHelper.queryOne(Id)>0)
                {

                    Toast.makeText(this, "该学号已存在", Toast.LENGTH_SHORT).show();
                    return;
                }
                    //Log.d("ning",Id);
                    mHelper.insert(user);
                    Toast.makeText(this, "添加成功", Toast.LENGTH_SHORT).show();
                break;
            case R.id.bt_delete:
                if(mHelper.deleteById(Id)>0)
                {
                    Toast.makeText(this, "删除成功", Toast.LENGTH_SHORT).show();
                }
                break;
            case R.id.bt_update:
                user=new User(Id,Name,Pn,Class);
                if(mHelper.update(user)>0)
                {
                    Toast.makeText(this, "修改成功", Toast.LENGTH_SHORT).show();
                }
                break;
            case R.id.bt_all:
                List<User> list=mHelper.queryAll();
                for(User u:list)
                {
                    Log.d("ning",u.toString());
                }
                StringBuffer buffer=new StringBuffer();
                if(list.size()==0){
                    tv_show.setText("没有数据");
                }else {
                    for (int i=0;i<list.size();i++){
                        user= list.get(i);
                        buffer.append("id:" +user.getId()+
                                "用户名:"+user.getName()+
                                "手机号:"+user.getPn()+
                                "班级:"+user.getCs()+"\n");
                    }
                    tv_show.setText(buffer);
                }
                break;
        }
    }
}

package database;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import entity.Day;
import entity.User;

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

public class UserDBHelper extends SQLiteOpenHelper {
    private static final String DB_NAME="user.db";
    private static final String TABLE_NAME="user_info";
    private static final String TABLE_NAME1="day_info";
    private static final int DB_VERSION=1;
    private static UserDBHelper mHelper=null;
    private SQLiteDatabase mRDB=null;
    private SQLiteDatabase mWDB=null;

    private UserDBHelper(Context context){
        super(context,DB_NAME,null,DB_VERSION);
    }
    public static UserDBHelper getInstance(Context context){
        if(mHelper==null)
        {
            mHelper=new UserDBHelper(context);
        }
        return mHelper;
    }
    public SQLiteDatabase openReadLink(){
        if(mRDB==null||!mRDB.isOpen())
        {
            mRDB=mHelper.getReadableDatabase();
        }
        return mRDB;
    }
    public SQLiteDatabase openWriteLink(){
        if(mWDB==null||!mWDB.isOpen())
        {
            mWDB=mHelper.getWritableDatabase();
        }
        return mWDB;
    }
    public void closeLink(){
        if(mRDB!=null&&mRDB.isOpen())
        {
            mRDB.close();
            mRDB=null;
        }
        if(mWDB!=null&&mWDB.isOpen())
        {
            mWDB.close();
            mWDB=null;
        }
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
        String sql="CREATE TABLE IF NOT EXISTS "+TABLE_NAME+"("+
                " Id VARCHAR NOT NULL,"+
                " Name VARCHAR NOT NULL,"+
                " Pn VARCHAR NOT NULL,"+
                " Class VARCHAR NOT NULL)";
        db.execSQL(sql);
        sql="CREATE TABLE IF NOT EXISTS "+TABLE_NAME1+"("+
                " keyword VARCHAR NOT NULL,"+
                " content VARCHAR NOT NULL,"+
                " createdtime VARCHAR NOT NULL,"+
                " id VARCHAR NOT NULL)";
        db.execSQL(sql);
    }

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

    }
    public void insert(User user)
    {
        Log.d("ning",user.Id);
        ContentValues values=new ContentValues();
        values.put("Id",user.Id);
        values.put("Name",user.Name);
        values.put("Pn",user.Pn);
        values.put("Class",user.Cs);
        mWDB.insert(TABLE_NAME,null,values);
    }
    public int insertDay(Day day)
    {
        ContentValues values=new ContentValues();
        values.put("keyword",day.keyword);
        values.put("content",day.content);
        values.put("createdTime",day.createdTime);
        values.put("id",day.id);
        mWDB.insert(TABLE_NAME1,null,values);
        int a=1;
        return a;
    }
    public long deleteById(String Id)
    {
        return mWDB.delete(TABLE_NAME,"Id=?",new String[]{Id});
    }
    public long update(User user)
    {
        ContentValues values=new ContentValues();
        values.put("Id",user.Id);
        values.put("Name",user.Name);
        values.put("Pn",user.Pn);
        values.put("Class",user.Cs);
        return mWDB.update(TABLE_NAME,values,"Id=?",new String[]{user.Id});
    }
    public List<User> queryAll(){
        List<User> list=new ArrayList<>();
        Cursor cursor=mRDB.query(TABLE_NAME,null,null,null,null,null,null);
        while (cursor.moveToNext()){
            User user=new User();
            user.Id=cursor.getString(0);
            user.Name=cursor.getString(1);
            user.Pn=cursor.getString(2);
            user.Cs=cursor.getString(3);
            list.add(user);
        }
        return list;
    }
    public List<Day> queryAllDay(){
        List<Day> list=new ArrayList<>();
        Cursor cursor=mRDB.query(TABLE_NAME1,null,null,null,null,null,null);
        while (cursor.moveToNext()){
            Day day=new Day();
            day.keyword=cursor.getString(0);
            day.content=cursor.getString(1);
            day.createdTime=cursor.getString(2);
            day.id=cursor.getString(3);
            list.add(day);
        }
        return list;
    }
    public int queryOne(String Id){
        List<User> list1=new ArrayList<>();
        Cursor cursor=mRDB.query(TABLE_NAME,null,"Id=?",new String[]{Id},null,null,null);
        int a=0;
        while (cursor.moveToNext()){
            User user=new User();
            user.Id=cursor.getString(0);
            user.Name=cursor.getString(1);
            user.Pn=cursor.getString(2);
            user.Cs=cursor.getString(3);
            a=1;
            list1.add(user);
        }
        return a;
    }

}