1 class abc
 2 {
 3     public abc()
 4     {
 5         system.out.println("我是无参构造函数");
 6     }
 7     public abc(string str)
 8     {
 9         system.out.println("我是有参构造函数");
10     }
11 }
12 class Home
13 {
14     public static main()
15     {
16         abc a = new abc();
17         abc b = new abc("传参");
18     }
19 }