Name.java
import java.util.*;
public class Name implements Comparable
{
private String firstName,lastName;
public Name(String firstName,String lastName)
{
if(firstName==null || lastName==null)
{
throw new NullPointerException();
}
this.firstName=firstName;
this.lastName=lastName;
}
public String firstName()
{
return firstName;
}
public String lastName()
{
return lastName;
}
public boolean equals(Object o)
{
if(!(o instanceof Name))
return false;
Name n=(Name)o;
return n.firstName.equals(firstName)&& n.lastName.equals(lastName);
}
public int hashcode()
{
return 31*firstName.hashCode()+lastName.hashCode();
}
public String toString()
{
return firstName+""+lastName;
}
public int compareTo(Object o)
{
Name n=(Name)o;
int lastCmp=lastName.compareTo(n.lastName);
return (lastCmp!=0 ? lastCmp :firstName.compareTo(n.firstName));
}
}
_________________________
NameSort.java
import java.util.*;
class NameSort
{
public static void main(String args[])
{
Name n=new Name("niaho","sirigeleng");
System.out.println(n);
}
}
运行结果 niahosirig