JAVA面向对象学习——java面向对象概念———一个简单的继承示例——构造器
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构造器
子类是不继承父类的构造器(构造方法或者构造函数)的,它只是调用(隐式或显式)。
如果父类的构造器带有参数,则必须在子类的构造器中显式地通过 super 关键字调用父类的构造器并配以适当的参数列表。
如果父类构造器没有参数,则在子类的构造器中不需要使用 super 关键字调用父类构造器,系统会自动调用父类的无参构造器。
class SuperClass { private int n; SuperClass(){ System.out.println("SuperClass()"); } SuperClass(int n) { System.out.println("SuperClass(int n)"); this.n = n; } }
// SubClass 类继承 class SubClass extends SuperClass{ private int n; SubClass(){ // 自动调用父类的无参数构造器 System.out.println("SubClass"); } public SubClass(int n){ super(300); // 调用父类中带有参数的构造器 System.out.println("SubClass(int n):"+n); this.n = n; } }
// SubClass2 类继承 class SubClass2 extends SuperClass{ private int n; SubClass2(){ super(300); // 调用父类中带有参数的构造器 System.out.println("SubClass2"); } public SubClass2(int n){ // 自动调用父类的无参数构造器 System.out.println("SubClass2(int n):"+n); this.n = n; } }
public class TestSuperSub{ public static void main (String args[]){ System.out.println("------SubClass 类继承------"); SubClass sc1 = new SubClass(); SubClass sc2 = new SubClass(100); System.out.println("------SubClass2 类继承------"); SubClass2 sc3 = new SubClass2(); SubClass2 sc4 = new SubClass2(200); } }
class SuperClass { private int n; SuperClass() { System.out.println("SuperClass()"); } SuperClass(int n) { System.out.println("SuperClass(int n)"); this.n = n; } } class SubClass extends SuperClass { private int n; SubClass() { System.out.println("SubClass"); } public SubClass(int n) { super(300); System.out.println("SubClass(int n):"+n); this.n = n; } } class SubClass2 extends SuperClass { private int n; SubClass2() { super(300); System.out.println("SubClass2"); } public SubClass2(int n) { System.out.println("SubClass2(int n):"+n); this.n = n; } } public class TestSuperSub
{ public static void main (String args[])
{ System.out.println("-------------------------"); SubClass sc1 = new SubClass(); System.out.println("-----------------"); SubClass sc2 = new SubClass(100); System.out.println("-----------------------------------------"); System.out.println("-----------------------------------"); SubClass2 sc3 = new SubClass2(); System.out.println("-------------------------------"); SubClass2 sc4 = new SubClass2(200); } }
标签:JAVA,示例,int,SubClass2,System,SubClass,面向对象,println,out 来源: https://www.cnblogs.com/xiaobaibailongma/p/15834239.html