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[java]类&抽象类&接口分别作为方法参数和返回值

2017-06-08 21:43 573 查看

一参数

1,类名作为参数

package com.ma.demo;

public class People {
void show() {
System.out.println("people show");
}
}
---
package com.ma.demo;

public class PeopleDemo {
void method(People p) {
p.show();
}
}
---
package com.ma.demo;

public class Test {
public static void main(String[] args) {
People p = new People();
PeopleDemo pd = new PeopleDemo();
pd.method(p);
}
}
----

2,抽象类做为参数

package com.ma.demo2;

abstract class People {
abstract void show();
}
---
package com.ma.demo2;

public class PeopleDemo {
void method(People p) {
p.show();
}
}
---
package com.ma.demo2;

public class Student extends People {

@Override
void show() {
// TODO Auto-generated method stub
System.out.println("student show");
}

}
---
package com.ma.demo2;

public class Test {
public static void main(String[] args) {
People p = new Student();
PeopleDemo pd = new PeopleDemo();
pd.method(p);
}
}
------

3,接口做为参数

package com.ma.demo3;

interface People {
public abstract void show();
}
---
package com.ma.demo3;

public class PeopleDemo {
void method(People p) {
p.show();
}
}
---
package com.ma.demo3;

public class Student implements People {

@Override
public void show() {
// TODO Auto-generated method stub
System.out.println("student show");
}

}
---
package com.ma.demo3;

public class Test {
public static void main(String[] args) {
People p = new Student();
PeopleDemo pd = new PeopleDemo();
pd.method(p);
}
}
------

二.返回值

1,类名作为返回值

package com.ma.demo4;

public class People {
void show() {
System.out.println("people show");
}
}
---
package com.ma.demo4;

public class PeopleDemo {
People method() {
return new People();
}
}
---
package com.ma.demo4;

public class Test {
public static void main(String[] args) {
PeopleDemo pd = new PeopleDemo();

People p = pd.method();
p.show();
}
}
------

2,抽象类作为返回值

package com.ma.demo5;

abstract class People {
public abstract void show();
}
---
package com.ma.demo5;

public class PeopleDemo {
Student method() {
return new Student();
}
}
---
package com.ma.demo5;

public class Student extends People {

@Override
public void show() {
// TODO Auto-generated method stub
System.out.println("student show");
}

}
---
package com.ma.demo5;

public class Test {
public static void main(String[] args) {
PeopleDemo pd = new PeopleDemo();
People p = pd.method();
p.show();
}
}
----

3,接口作为返回值

package com.ma.demo6;

interface People {
public abstract void show();
}
--
package com.ma.demo6;

public class PeopleDemo {
People method() {
return new Student();
}
}
--
package com.ma.demo6;

public class Student implements People {

@Override
public void show() {
// TODO Auto-generated method stub
System.out.println("student show");
}

}
----
package com.ma.demo6;

public class Test {
public static void main(String[] args) {
PeopleDemo pd = new PeopleDemo();
People p = pd.method();
p.show();
}
}
----

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