我有两门课:
- MyActivity.Java
- DatabaseHandler.Java
我想从“getCurrentCar”方法中获取返回的字符串并将其放入 MyActivity.java
DatabaseHandler.Java:
public class DatabaseHandler extends SQLiteOpenHelper {
public Car getCurrentCar() {
SQLiteDatabase db = getWritableDatabase();
String sql = "SELECT " + KEY_ID + "," + KEY_IMAGE + " FROM " + TABLE_CARS + "ORDER BY RANDOM() LIMIT 1";
Cursor cursor = db.rawQuery(sql, new String[] {});
Car car = null;
try {
if (cursor.moveToFirst()) {
car = new Car(Integer.parseInt(cursor.getString(0)), cursor.getString(1), cursor.getString(2), cursor.getString(3));
}
}
finally {
if (cursor != null && !cursor.isClosed()) {
cursor.close();
}
db.close();
}
return car;
}
}
我已经尝试过,但参数要求上下文。
//DatabaseHandler handler = new DatabaseHandler(contexthere);
DatabaseHandler handler = new DatabaseHandler();
handler.getCurrentCar();
我想知道如何获取该返回值并将其放入 MyActivity.java 中,以便我可以使用 BitmapFactory 重新创建图像。
谢谢
最佳答案
Context
表示当前运行时:
protected void onCreate(Bundle savedInstanceState) {
...........
...........
// you should instantiate 'DatabaseHandler' here
DatabaseHandler db = new DatabaseHandler(this); // "this" refer to the context
..........
..........
// insert the rows
db.createCar(new Car("Sesame street A","23423","anImage1"));
db.createCar(new Car("Sesame street B","43543","anImage2"));
// get the rows which you mean string
for(Car cars : db.getCurrentCar()){
String rows= "id : "+ cars.getID()+ " address : "+getAddress() + "postcode : "+getPostcode()+" image : "+getImage());
}
}
只需根据 Car
类中的“getter”方法名称调整 .getID(),getAddress(),getPostcode(),getImage()
即可,就像我一样可能会写错
** 上面的代码是我根据您通过链接共享的文件编写的。 (你的文件缺少 Car
类),但我只是预测它应该像上面这样:
关于java - 使用一个类中的方法到类中,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/24898262/