下列程序用GridLayout布局管理器将Frame分为1行3列,并放入Button构件,横线处应填入的语句是( )。 import java.awt.*; public class Test public static void main (String[] args) Frame frm=new Frame ( GridLayout ); ____________ frm.add (new Button( Button1 )); frm.add (new Button( Button2 )); frm.add (new Button( Button3 )); frm.setSize (300,300); frm.setVisible (true);
A.frm.setLayout (GridLayout (1,3));
B.setLayout (new GridLayout(1,3));
C.frm.setLayout (new GridLayout(3,1));
D.frm.setLayout (new GridLayout(1,3));