目录
用 [TOC]
来生成目录:
返回值类型
返回值类型
基本类型:(基本类型太简单,我不准备讲解)
引用类型:
类:返回的是该类的对象
抽象类:返回的是该抽象类的子类对象
接口:返回的是该接口的实现类的对象
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类名作为返回值-代码块
// <1>类作为返回值
class Student {
public void study() {
System.out.println("Good Good Study,Day Day Up");
}
}
class StudentDemo {
public Student getStudent() {
//Student s = new Student();
//return s;
return new Student();
}
}
class StudentTest2 {
public static void main(String[] args) {
StudentDemo sd = new StudentDemo();
Student s = sd.getStudent(); //new Student(); Student s = new Student();
s.study();
}
}
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抽象类作为返回值-代码块
// <2> 抽象类作为返回值
abstract class Person {
public abstract void study();
}
class PersonDemo {
public Person getPerson() {
//Person p = new Student();
//return p;
return new Student();
}
}
class Student extends Person {
public void study() {
System.out.println("Good Good Study,Day Day Up");
}
}
class PersonTest2 {
public static void main(String[] args) {
//需求:我要测试Person类中的study()方法
PersonDemo pd = new PersonDemo();
Person p = pd.getPerson(); //new Student(); Person p = new Student(); 多态
p.study();
}
}
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接口作为返回值-代码块
// <3> 接口作为返回值
//定义一个说的的接口
interface speak{
public abstract void speakeng();
}
class teacher implements speak{
public void speakeng(){
System.out.println("I can speak!");
}
}
class teacherDemo{
public speak show(){
return new teacher(); //返回的是该接口的实现类的对象
}
}
public class TeacherTest4 {
public static void main(String[] args) {
teacherDemo td =new teacherDemo();
speak l= td.show(); //new teacher(); speak l=new teacher(); 多态
l.speakeng();
}
}