Interface specifies methods

Question

Write an interface named Nameable that specifies the following methods:

public void setName(String n)
public String getName()

This is what I got:

 public interface Nameable{ 
 public void setName(String n){ 
 n =name; } 
 public String getName() {
 return n; } }

is this correct or is there a better way of doing this??

Answer 1

An interface doesn't specify implementation, so no, this isn't correct.

You must separate the definition of the available methods (the interface) and the implementation (the class) :

public interface Nameable{ 
 public void setName(String n); 
 public String getName();
}
public class Named implements Nameable {
 private String name;
 public void setName(String n){ 
 this.name = n;
 } 
 public String getName() {
 return this.name;
 }
}

Answer 2

No, you don't define a method in your interface, you only declare them. A class which implements that interface later on, provides the implementation of the method.

is this correct or is there a better way of doing this??

Better way? Yes. Copy this code and paste in your favorite IDE. It will tell you where you are wrong, with so many Red-Marks.

IDE like Eclipse suddenly starts screaming if you create such an interface, and you can tell it to correct it for you. Then you can see the magic.

Answer 3

You must remember that interfaces only provide method declarations, and do not provide implementation. That is up to the implemented class.

public interface Nameable
{ 
 public void setName(String n);
 public String getName();
}
public class NameableImplmentation implments Nameable
{
 public void setName(String n)
 { 
 //insert code 
 } 
 public String getName() 
 {
 //insert code
 } 
}

Answer 4

Your code will gives you Abstract methods do not specify a body.

all the methods of interface are by default abstract, and abstract method has no body, see here abstract

An interface is a group of related methods with empty bodies, but in your code all the methods having the body so that will not compile, see how interface work

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