android如何将对象传递给新类
我有以下活动android如何将对象传递给新类,android,oop,Android,Oop,我有以下活动 public class BmiHistory extends Activity { public Cursor cursor; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //setContentView(R.layout.bmihistory); final DatabaseHandler databa
public class BmiHistory extends Activity {
public Cursor cursor;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.bmihistory);
final DatabaseHandler databaseOpen = new DatabaseHandler(this);
final SQLiteDatabase db = databaseOpen.getReadableDatabase();
Cursor c1 = db.rawQuery("select * from bmi", null);
startManagingCursor(c1);
c1.moveToFirst();
this.cursor = c1;
while(!c1.isAfterLast()) {
System.out.println(c1.getString(2));
c1.moveToNext();
}
c1.close();
BmiGraph drawView = new BmiGraph(this);
drawView.setBackgroundColor(Color.WHITE);
setContentView(drawView);
}
}
我在这次活动中调用了以下类
public class BmiGraph extends View {
Paint paint = new Paint();
public BmiGraph(BmiHistory context) {
super(context);
// TODO Auto-generated constructor stub
System.out.println(context.toString());
}
public void onDraw(Canvas canvas) {
paint.setColor(Color.BLACK);
paint.setStrokeWidth(3);
...
}
}
我的问题是如何使活动中光标的数据可供第二个类使用,以便绘制图形
非常感谢您可以修改BmiGraph类的构造函数以接受光标作为输入(请参见下文)。然后,您将可以从BmiGraph类中访问光标
public class BmiGraph extends View {
Paint paint = new Paint();
Cursor _someCursor;
public BmiGraph(BmiHistory context, Cursor someCursor) {
super(context);
// TODO Auto-generated constructor stub
System.out.println(context.toString());
_someCursor = someCursor
}
public void onDraw(Canvas canvas) {
paint.setColor(Color.BLACK);
paint.setStrokeWidth(3);
...
}
}
在
BmiGraph
中添加一个setter方法,并从BmiHistory
调用它。谢谢K-ballo,我尝试过了,但我不太了解语义它主要是语法,而不是语义。。如果你想编写Android应用程序,你必须学习Java。我正在尝试-你能给我举个例子吗?不,对不起,我不能在一个例子中综合如何用Java编程。拿起一个教程,我相信有很多好的!