import java.util.*;
public class BasicContainer {
public static void main(String[] args) {
Collection c = new HashSet();
c.add("hello");
c.add(new Name("f1","l1"));
c.add(new Integer(100));
c.remove("hello");
c.remove(new Integer(100));
System.out.println
(c.remove(new Name("f1","l1")));
System.out.println(c);
}
}
class Name implements Comparable {
private String firstName,lastName;
public Name(String firstName, String lastName) {
this.firstName = firstName; this.lastName = lastName;
}
public String getFirstName() { return firstName; }
public String getLastName() { return lastName; }
public String toString() { return firstName + " " + lastName; }
public boolean equals(Object obj) {
if (obj instanceof Name) {
Name name = (Name) obj;
return (firstName.equals(name.firstName))
&& (lastName.equals(name.lastName));
}
return super.equals(obj);
}
public int hashCode() {
return firstName.hashCode();
}
public int compareTo(Object o) {
Name n = (Name)o;
int lastCmp =
lastName.compareTo(n.lastName);
return
(lastCmp!=0 ? lastCmp :
firstName.compareTo(n.firstName));
}
}
remove是new出來的對象,hashmap是通過hashcode區分是不是同一個對象的。
兩個對象的hashcode不一樣,除非你重寫一下name類的hashcode獲取方式。