helloworld教程的gitee源码地址+sqlite demo

https://gitee.com/hwdroid，已经fork

HelloWorld/ app / src / main / java / com / ttit / core / sqlite
https://www.bilibili.com/video/BV1PE411u7ox

package com.example.helloworld;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;


public class SqliteActivity extends AppCompatActivity implements View.OnClickListener {

    private Context mContext;
    private Button btn_insert;
    private Button btn_query;
    private Button btn_update;
    private Button btn_delete;
    private SQLiteDatabase db;
    private MyDBOpenHelper myDBHelper;
    private StringBuilder sb;
    private int i = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sqlite);
        mContext = this;
        myDBHelper = new MyDBOpenHelper(mContext, "my.db", null, 2);
        bindViews();
        db = myDBHelper.getWritableDatabase();
    }

    private void bindViews() {
        btn_insert = (Button) findViewById(R.id.btn_insert);
        btn_query = (Button) findViewById(R.id.btn_query);
        btn_update = (Button) findViewById(R.id.btn_update);
        btn_delete = (Button) findViewById(R.id.btn_delete);

        btn_query.setOnClickListener(this);
        btn_insert.setOnClickListener(this);
        btn_update.setOnClickListener(this);
        btn_delete.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        //db = myDBHelper.getWritableDatabase();
        switch (v.getId()) {
            case R.id.btn_insert:
                ContentValues values1 = new ContentValues();
                values1.put("name", "呵呵~" + i);
                i++;
                //参数依次是：表名，强行插入null值得数据列的列名，一行记录的数据
                db.insert("person", null, values1);
                Toast.makeText(mContext, "插入完毕~", Toast.LENGTH_SHORT).show();
                break;
            case R.id.btn_query:
                sb = new StringBuilder();
                //参数依次是:表名，列名，where约束条件，where中占位符提供具体的值，指定group by的列，进一步约束
                //指定查询结果的排序方式
                Cursor cursor = db.query("person", null, null, null, null, null, null);
                if (cursor.moveToFirst()) {
                    do {
                        int pid = cursor.getInt(cursor.getColumnIndex("personid"));
                        String name = cursor.getString(cursor.getColumnIndex("name"));
                        sb.append("id：" + pid + "：" + name + "\n");
                    } while (cursor.moveToNext());
                }
                cursor.close();
                Toast.makeText(mContext, sb.toString(), Toast.LENGTH_SHORT).show();
                break;
            case R.id.btn_update:
                ContentValues values2 = new ContentValues();
                values2.put("name", "嘻嘻~");
                //参数依次是表名，修改后的值，where条件，以及约束，如果不指定三四两个参数，会更改所有行
                db.update("person", values2, "name = ?", new String[]{"呵呵~2"});
                break;
            case R.id.btn_delete:
                //参数依次是表名，以及where条件与约束
                db.delete("person", "personid = ?", new String[]{"3"});
                break;
        }
    }
}

package com.example.helloworld;

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

public class MyDBOpenHelper extends SQLiteOpenHelper {
    private static final String TAG = "ttit";

    public MyDBOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory,
                          int version) {
        super(context, name, null, version);
    }

    @Override
    //数据库第一次创建时被调用
    public void onCreate(SQLiteDatabase db) {
        Log.e(TAG, "MyDBOpenHelper: 执行了 onCreate");
        db.execSQL("CREATE TABLE person(personid INTEGER PRIMARY KEY AUTOINCREMENT,name VARCHAR(20))");

    }

    //软件版本号发生改变时调用
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.e(TAG, "MyDBOpenHelper: 执行了onUpgrade");
        db.execSQL("ALTER TABLE person ADD phone VARCHAR(12) NULL");
    }
}

本文地址：https://blog.csdn.net/weixin_43292547/article/details/110672420