Android 新增页面使用sqlite实现增加数据

要在 Android 中使用 SQLite 实现新增数据，需要执行以下步骤：

1. 首先，创建一个 SQLite 数据库并创建一个表，用于存储数据。

public class DatabaseHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "mydatabase.db";
    private static final int DATABASE_VERSION = 1;
    private static final String TABLE_NAME = "mytable";
    private static final String COLUMN_ID = "id";
    private static final String COLUMN_NAME = "name";
    private static final String COLUMN_AGE = "age";
    
    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String createTable = "CREATE TABLE " + TABLE_NAME + " (" +
                COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                COLUMN_NAME + " TEXT, " +
                COLUMN_AGE + " INTEGER)";
        db.execSQL(createTable);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(db);
    }
}

2. 在需要添加数据的 Activity 中，实例化 DatabaseHelper 类，并获取 SQLiteDatabase 对象。

DatabaseHelper dbHelper = new DatabaseHelper(this);
SQLiteDatabase db = dbHelper.getWritableDatabase();

3. 创建一个 ContentValues 对象，将要插入的数据放入其中。

ContentValues contentValues = new ContentValues();
contentValues.put(DatabaseHelper.COLUMN_NAME, "John");
contentValues.put(DatabaseHelper.COLUMN_AGE, 25);

4. 使用 insert() 方法将数据插入到表中。

long result = db.insert(DatabaseHelper.TABLE_NAME, null, contentValues);
if (result == -1) {
    Toast.makeText(this, "Failed to add data.", Toast.LENGTH_SHORT).show();
} else {
    Toast.makeText(this, "Data added successfully.", Toast.LENGTH_SHORT).show();
}

完整的示例代码如下所示：

public class MainActivity extends AppCompatActivity {
    private EditText etName, etAge;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        etName = findViewById(R.id.et_name);
        etAge = findViewById(R.id.et_age);

        findViewById(R.id.btn_add).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name = etName.getText().toString().trim();
                int age = Integer.parseInt(etAge.getText().toString().trim());

                DatabaseHelper dbHelper = new DatabaseHelper(MainActivity.this);
                SQLiteDatabase db = dbHelper.getWritableDatabase();

                ContentValues contentValues = new ContentValues();
                contentValues.put(DatabaseHelper.COLUMN_NAME, name);
                contentValues.put(DatabaseHelper.COLUMN_AGE, age);

                long result = db.insert(DatabaseHelper.TABLE_NAME, null, contentValues);
                if (result == -1) {
                    Toast.makeText(MainActivity.this, "Failed to add data.", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(MainActivity.this, "Data added successfully.", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}