Java中父类和子类之间的转换操作示例

本文实例讲述了Java中父类和子类之间的转换操作。分享给大家供大家参考，具体如下：

一、父类引用强转成为子类引用

package learn20180720;
 
public class People {
 
 private String name;
 private Integer age;
 private Double height;
 
 public People(){
 this.name = \"\";
 this.age = 0 ;
 this.height = 0.0;
 }
 
 public People(String name, Integer age, Double height) {
 super();
 this.name = name;
 this.age = age;
 this.height = height;
 }
 
 public String getName() {
 return name;
 }
 
 public void setName(String name) {
 this.name = name;
 }
 
 public Integer getAge() {
 return age;
 }
 
 public void setAge(Integer age) {
 this.age = age;
 }
 
 public Double getHeight() {
 return height;
 }
 
 public void setHeight(Double height) {
 this.height = height;
 }
 
 public void tellObjectName(People p) {
 System.err.println(p.name);
 }
 
 public void sayInformation() {
 System.err.println(\"我的名字叫做：\"+this.name+\"我的年龄是：\"+this.age+\"我的身高是\"+this.height);
 }
}

package learn20180720;
public class Chinese extends People{
 
 private String country;
 
 public Chinese(){
 super();
 country = \"\";
 }
 
 public Chinese(String aname,Integer aage,Double aheight) {
 super(aname,aage,aheight);
 this.country = \"中国\";
 }
 
 public String getCountry() {
 return country;
 }
 
 public void setCountry(String country) {
 this.country = country;
 }
 
 
 public void sayInformation() {
 // TODO Auto-generated method stub
 System.err.println(\"我的名字叫做：\"+this.getName()+\"  我的年龄是：\"+this.getAge()+\"  我的身高是：\"+this.getHeight()+\"  我的国家是：\"+this.country);
 }
}

package learn20180720;
public class TestPeCh {
 
 public static void main(String[] args) {
 // TODO Auto-generated method stub
 People p1 = new Chinese();
 
 Chinese c1 = (Chinese)p1;
 
 }
}

Java中父类和子类之间的转换操作示例

可以看到，p1无法访问子类中的特有的方法（父类引用可以访问子类中重写父类中的方法），但是强转成为子类类型的引用c1之后，c1就可以访问子类中所有的方法啦。

二、父类不可以强转成为子类

package learn20180720;
public class TestPeCh {
 
 public static void main(String[] args) {
 // TODO Auto-generated method stub
 People p1 = new People();
 
 Chinese c1 = (Chinese)p1;
 
 }
}

Java中父类和子类之间的转换操作示例