計算產生第幾個新的類別

技巧：設定變數為static
code

package javahomework;

import javax.swing.JOptionPane;

class TestC {
 static int count = 0;

 public static TestC getInstance() {
  TestC x = new TestC();
  count++;
  return x;
 }

 public static String get_count() {
  return String.valueOf(count);
 }
}

public class HW11 {
 public static void main(String args[]) {
  TestC c1 = TestC.getInstance();
  TestC c2 = TestC.getInstance();
  TestC c3 = TestC.getInstance();
  JOptionPane.showMessageDialog(null, TestC.get_count());
 }

}