JAVA类的继承之多态特性

　　父类可以接收子类的实例，方法的覆盖，属性的隐藏，这些都使我非常疑惑，今天有点时间记录之。

　　话不多说，直接上代码上结果

1.

public class TestDto{ public static void main(String[] args) { ClassInitializeChild child=new ClassInitializeChild(); System.out.println(child.name); } } class ClassInitializeParent{ public String name="parent"; public void print(){ System.out.println("parent="+name); } public ClassInitializeParent(){ print(); } } class ClassInitializeChild extends ClassInitializeParent{ public String name="child"; public void print(){ System.out.println("child="+name); } public ClassInitializeChild(){ print(); } }

　　结果：

　　

child=null child=child child

2.

public class TestDto{ public static void main(String[] args) { ClassInitializeParent parent=new ClassInitializeChild(); System.out.println(parent.name); } } class ClassInitializeParent{ public String name="parent"; public void print(){ System.out.println("parent="+name); } public ClassInitializeParent(){ print(); } } class ClassInitializeChild extends ClassInitializeParent{ public String name="child"; public void print(){ System.out.println("child="+name); } public ClassInitializeChild(){ print(); } }

　　结果：

　　

child=null child=child parent

3.

public class TestDto{ public static void main(String[] args) { ClassInitializeParent parent=new ClassInitializeChild(); parent.print(); } } class ClassInitializeParent{ public String name="parent"; public void print(){ System.out.println("parent="+name); } } class ClassInitializeChild extends ClassInitializeParent{ public String name="child"; public void print(){ System.out.println("child="+name); } }

　　结果：

　　

child=child

4.

public class TestDto{ public static void main(String[] args) { ClassInitializeParent parent=new ClassInitializeParent(); parent.print(); } } class ClassInitializeParent{ public String name="parent"; public void print(){ System.out.println("parent="+name); } } class ClassInitializeChild extends ClassInitializeParent{ public String name="child"; public void print(){ System.out.println("child="+name); } }

　　结果：

parent=parent

 

转载于:https://www.cnblogs.com/wuyouwei/p/6274190.html

相关资源：java 三大特性--封装、继承和多态理解