【Android开发基础】SQLite开发复刻通讯录、记事本、计算机

由于篇幅所限，这里只展示如何使用SQLite数据库创建一个简单的通讯录应用程序的核心函数。请注意，这不是一个完整的应用程序，而是展示了如何使用SQLite来存储和检索数据的核心方法。

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
 
public class ContactsDatabaseHelper extends SQLiteOpenHelper {
 
    private static final String TABLE_NAME = "contacts";
    private static final String COL_ID = "id";
    private static final String COL_NAME = "name";
    private static final String COL_PHONE = "phone";
 
    public ContactsDatabaseHelper(Context context) {
        super(context, "contacts.db", null, 1);
    }
 
    @Override
    public void onCreate(SQLiteDatabase db) {
        String createTableStatement = "CREATE TABLE " + TABLE_NAME + " (" + COL_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + COL_NAME + " TEXT, " + COL_PHONE + " TEXT)";
        db.execSQL(createTableStatement);
    }
 
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Implement schema migration logic if needed
    }
 
    public boolean insertContact(String name, String phone) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues cv = new ContentValues();
        cv.put(COL_NAME, name);
        cv.put(COL_PHONE, phone);
 
        long result = db.insert(TABLE_NAME, null, cv);
        return result != -1;
    }
 
    public Cursor getAllContacts() {
        SQLiteDatabase db = this.getReadableDatabase();
        return db.query(TABLE_NAME, new String[]{COL_ID, COL_NAME, COL_PHONE}, null, null, null, null, null);
    }
 
    public Cursor getContact(int id) {
        SQLiteDatabase db = this.getReadableDatabase();
        return db.query(TABLE_NAME, new String[]{COL_ID, COL_NAME, COL_PHONE}, COL_ID + "=?", new String[]{String.valueOf(id)}, null, null, null, null);
    }
 
    public boolean updateContact(int id, String name, String phone) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues cv = new ContentValues();
        cv.put(COL_NAME, name);
        cv.put(COL_PHONE, phone);
 
        int result = db.update(TABLE_NAME, cv, COL_ID + "=?", new String[]{String.valueOf(id)});
        return result > 0;
    }
 
    public boolean deleteContact(int id) {
        SQLiteDatabase db = this.getWritableDatabase();
        int result = db.de