Java入门练习题的源代码(Eclipse导入即可)

package chapter2.e2; import java.applet.*; import java.awt.*; import java.awt.event.*; public class AAIfillOval extends Applet implements ItemListener { /** * */ private static final long serialVersionUID = 1L; CheckboxGroup cg; Checkbox ch1, ch2, ch3; Choice choice; int i = 1; int k = 90; public void init() { cg = new CheckboxGroup(); ch1 = new Checkbox("red", true, cg); ch2 = new Checkbox("yellow", false, cg); ch3 = new Checkbox("blue", false, cg); add(ch1); ch1.addItemListener(this); add(ch2); ch2.addItemListener(this); add(ch3); ch3.addItemListener(this); choice = new Choice(); choice.addItem("90"); choice.addItem("70"); choice.addItem("50"); choice.addItem("30"); choice.addItem("10"); add(choice); choice.addItemListener(this); } public void itemStateChanged(ItemEvent e) { if (ch1.getState()) { i = 1; } else if (ch2.getState()) { i = 2; } else { i = 3; } if(e.getSource() == choice){ k = Integer.parseInt(choice.getSelectedItem()); } } public void paint(Graphics g){ if(i==1){ g.setColor(Color.red); g.fillOval(10, 10, k, k); } if(i==2){ g.setColor(Color.yellow); g.fillOval(10, 10, k, k); } if(i==3){ g.setColor(Color.blue); g.fillOval(10, 10, k, k); } try { Thread.sleep(300); repaint(); } catch (Exception e) { // TODO: handle exception } } }