用Java实现多重继承

Question

I'm trying to figure out how to implement multiple interfaces in my java program.

I want my program to implement a college football player class that incorporates the three classes (footballPlayer, student and person).

public class app {
public static void main(String[] args)
   { 
     student st1 = new student("Zack","Mills",22); 
     System.out.println(st1.getAllInfo()); 
     footballPlayer fp1 = new footballPlayer("Zack","Mills",22,5.9f, 240,"Junior","Running Back");
   System.out.println(fp1.getAllInfo());
   } 
 }

public class person {
 //---------Declaring attributes---- 
 private String firstName; 
 private String lastName; 
 private int age; 
 //------------------------------ 
 //----------Constructor------------ 
 person(String a, String b, int c) 
 { 
      firstName = a; 
      lastName = b; 
      age = c; 
 } 
 //---------- METHODS -------- 
 String getInfo() 
 { 
      return "NAME = "+getFirstName()+ " "+getLastName()+" "+"Age = "+ getAge(); 
 } 
 //------------------------------------------------ 
 /** 
  * @return the firstName 
  */ 
 public String getFirstName() { 
      return firstName; 
 } 
 /** 
  * @param firstName the firstName to set 
  */ 
 public void setFirstName(String firstName) { 
      this.firstName = firstName; 
 } 
 /** 
  * @return the lastName 
  */ 
 public String getLastName() { 
      return lastName; 
 } 
 /** 
  * @param lastName the lastName to set 
  */ 
 public void setLastName(String lastName) { 
      this.lastName = lastName; 
 } 
 /** 
  * @return the age 
  */ 
 public int getAge() { 
      return age; 
 } 
 /** 
  * @param age the age to set 
  */ 
 public void setAge(int age) { 
      this.age = age; 
  } 


}

public class footballPlayer extends person {

//-----------FOOTBALL PLAYER ATTRIBUTES----------------------------
private float height; 
private float weight; 
private String experience; 
private String position; 




footballPlayer(String fn, String ln, int ag,float ht, float wt, String exp, String pos) 
{ 
    super(fn, ln, ag); 
    height = ht; 
    weight = wt; 
    experience = exp; 
    position = pos; 
} 
/** 
 * @return the height 
 */ 
public float getHeight() { 
    return height; 
} 
/** 
 * @param height the height to set 
 */ 
public void setHeight(float height) { 
    this.height = height; 
} 
/** 
 * @return the weight 
 */ 
public float getWeight() { 
    return weight; 
} 
/** 
 * @param weight the weight to set 
 */ 
public void setWeight(float weight) { 
    this.weight = weight; 
} 
/** 
 * @return the experience 
 */ 
 public String getExperience() { 
     return experience; 
} 
/** 
 * @param experience the experience to set 
 */ 
public void setExperience(String experience) { 
     this.experience = experience; 
} 
/** 
 * @return the position 
 */ 
public String getPosition() { 
    return position; 
} 
/** 
 * @param position the position to set 
 */ 
public void setPosition(String position) { 
    this.position = position; 
} 
String getAllInfo() 
{ 
    return getFirstName() + " " + getLastName() + " " + getAge() + " " + " " + getHeight() + " " + getWeight() + " " + getExperience() + " " + getPosition(); 
} 

 private String status; 
}

public class student extends person {

private String status;
 student(String informedFirstName, String informedLastName, int informedAge) 
{ 
   super(informedFirstName, informedLastName, informedAge); 
   if (getAge() <= 25) status = "Traditional";

} 
String getStatus() 
{ 
   return this.status; 
} 
public void setStatus(String status) 
{ 
   this.status = status; 
} 

String getAllInfo() 
{ 
   return getFirstName() + " " + getLastName() + " " + getAge() + " " + getStatus(); 
 } 
}

 public class CollegefootballPlayer {

//attributes of football player and student

}

Answer 1

I would add to the comments as well but don't have the reputation to do so yet. Anyway, the others are correct about lack of multiple inheritance in Java. In addition to working with interfaces there is also some discussion about object composition instead of inheritance.

Here's a thread on the subject:

Advantages of composition over inheritance in Java

Composition comes with a great deal of flexibility. The member objects of your new class are typically private, making them inaccessible to the client programmers who are using the class. This allows you to change those members without disturbing existing client code. You can also change the member objects at run time, to dynamically change the behavior of your program. Inheritance, which is described next, does not have this flexibility since the compiler must place compile-time restrictions on classes created with inheritance.

So you could maintain a person class with a list of attributes like occupation and hobbies/sports.