android SQLIte数据库数据获取

Question

android 如何实现勾选checkbox后，文本框中显示之前写入到SQLite数据库中的内容

Answer 1

用CompoundButton类的复选按钮，使用onCheckedChanged 方法实现，下面是一个例子可以代入执行：

CheckBox checkBox = findViewById(R.id.checkbox);
EditText editText = findViewById(R.id.edit_text);

checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
        editText.setEnabled(isChecked);
        if (isChecked) {
    
            String previousContent = getDataFromSQLite()；
            editText.setText(previousContent);
        } 
else {
           
            editText.setText("");
        }
    }
});

private String getDataFromSQLite() {
    return "save result";
}

//如果你向获取sqlite的内容可以创建SQLiteOpenHelper 的子类，并使用onCreate ：
public class MyDatabaseHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "my_database.db";
    private static final int DATABASE_VERSION = 1;

    public MyDatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String createTableSql = "CREATE TABLE my_table (content TEXT)";
        db.execSQL(createTableSql);
    }

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

    }
}
MyDatabaseHelper dbHelper = new MyDatabaseHelper(context);
SQLiteDatabase db = dbHelper.getReadableDatabase();
String[] projection = { "content" };
Cursor cursor = db.query("my_table", projection, null, null, null, null, null);
if (cursor.moveToFirst()) {
    String previousContent = cursor.getString(0);
}

```