javaJDialog设置为模态后为什么对话框就变一点小了 告急！！！！

这是设置成模态后的图片

下面是非模态 不知道为什么 大神们帮我看一下 告急！！

对话框源代码 自定义的类 在主类里直接调用的 去掉了部分 但不影响运行
public class GamesetDialog {
private JPanel panel;
private JLabel choosenandu,choosediscaccount,discsize,jmin,jmax;
private JButton disccolor,confirm;
private JRadioButton primary,middle,high;
private JTextField account,min,max;
private ButtonGroup buttongroup;
public GamesetDialog(JFrame container) {
JDialog jj= new JDialog(container,"游戏设置",true);
Container c=jj.getContentPane();
c.setLayout(null);
choosenandu = new JLabel("选择关卡");
choosenandu.setBounds(5,20,100,20);c.add(choosenandu);
buttongroup=new ButtonGroup();
primary= new JRadioButton("初级");middle= new JRadioButton("中级");high= new JRadioButton("高级");
primary.setBounds(5,60,60,20);
middle.setBounds(70,60,60,20);
high.setBounds(135,60,60,20);
c.add(primary);c.add(middle);c.add(high);
buttongroup.add(primary);buttongroup.add(middle);buttongroup.add(high);
choosediscaccount = new JLabel("盘子数量(1-15)");
choosediscaccount.setBounds(5,100,100,20);c.add(choosediscaccount);
account=new JTextField();
account.setBounds(115,100,100,20);c.add(account);
discsize = new JLabel("盘子大小");
discsize.setBounds(5,140,100,20);c.add(discsize);
jmax=new JLabel("最大");max=new JTextField();
jmax.setBounds(5,170,30,20);max.setBounds(40,170,100,20);
c.add(jmax);c.add(max);
jmin=new JLabel("最小");min= new JTextField();
jmin.setBounds(170,170,50,20);min.setBounds(205,170,100,20);
c.add(jmin);c.add(min);
jj.pack();
//jj.setResizable(false);jj.setVisible(true); jj.setBounds(100,100,400,340);jj.setDefaultCloseOp

setPreferredSize(new Dimension(400, 340));

设置一下对话框的大小试试