循环列表gui

大家好我对第一个RadioButton中JList中的循环有问题它是正确的但是在第二个示例中如果我试图做另一个星号循环将会出错这是我的代码到目前为止。

import java.awt.*; import java.awt.event.*; import javax.swing.*; public class LOOPING extends JFrame implements ItemListener { JFrame jeframe = new JFrame("LOOPING"); JPanel jenel = new JPanel(); JLabel let = new JLabel("Choose a letter"); JRadioButton first = new JRadioButton("A"); JRadioButton second = new JRadioButton("B"); JRadioButton third = new JRadioButton("C"); JRadioButton fourth = new JRadioButton("D"); JList asterisk = new JList(); JLabel je = new JLabel(); DefaultListModel aslist = new DefaultListModel(); public LOOPING() { jenel.setLayout(null); jeframe.setVisible(true); jeframe.setBounds(330,100,200,370); jeframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); let.setBounds(10,10,100,20); first.setBounds(20,50,50,30); second.setBounds(20,110,50,30); third.setBounds(100,50,50,30); fourth.setBounds(100,110,50,30); asterisk.setBounds(07,150,170,170); je.setBounds(07,90,110,170); jenel.add(let); jenel.add(first); jenel.add(second); jenel.add(third); jenel.add(fourth); jenel.add(asterisk); jenel.add(je); first.addItemListener(this); second.addItemListener(this); third.addItemListener(this); fourth.addItemListener(this); getContentPane().add(jenel); jeframe.add(jenel); } public void itemStateChanged(ItemEvent e) { ItemSelectable beu; beu = e.getItemSelectable(); String s = "*"; if(beu == first) { for(int a=0; a<=4; a++) { for(int b=1; b<a; b++) System.out.print(" "); je.setText(je.getText() + s); aslist.addElement(je.getText()); asterisk.setModel(aslist); } } if(beu == second) { for(int v=1; v<=5; v++) { for(int j=v; j0; u--) { for(int i=u; i>0; i--) { je.setText(je.getText() + boo); System.out.print(" "); } aslist.addElement(je.getText()); asterisk.setModel(aslist); } } } public static void main(String [] args) { LOOPING lup = new LOOPING(); } } 

Answer 1

试试你的beu == second 。 你需要连接* s。 你目前只用一个 *设置文字

  if (beu == second) { for (int v = 1; v <= 5; v++) { String stars = ""; for (int j = v; j <= 5; j++) { stars += s; } je.setText(stars); System.out.println(); aslist.addElement(je.getText()); asterisk.setModel(aslist); } } 

产量

 ***** **** *** ** * 

为了这

  * ** *** **** ***** 

你需要两个循环，1个用于空格，另一个用于星号。 试试这个

  if (beu == third) { for (int m = 0; m < 6; m++) { String stars = ""; for (int k = 6; k >= m; k--) { System.out.print(" "); stars += " "; } for (int i = 1; i <= m; i++) { System.out.print("*"); stars += "*"; } je.setText(stars); aslist.addElement(je.getText()); asterisk.setModel(aslist); System.out.println(); } }