删除集合中的重复元素

实体类：

public class Book implements Comparable<Book>{
private int bookId;
public Book() {
// TODO Auto-generated constructor stub
}
public Book(int bookId){
this.bookId=bookId;
}
public int getBookId() {
return bookId;
}
@Override
public String toString() {
return "Book [bookId=" + bookId + "]";
}
@Override
public int compareTo(Book o) {
if(this.bookId>o.bookId){
return 1 ;
}else if(this.bookId<o.bookId){
return -1 ;
}else{
return 0;
}
}
}

操作及测试：

public class Test {
public static void main(String[] args){
List list=new ArrayList();
Book book1=new Book(1001);
Book book2=new Book(1002);
Book book3=new Book(1003);
Book book4=new Book(1003);
list.add(book1);
list.add(book2);
list.add(book3);
list.add(book4);
System.out.print(list);
for (int i = 0; i < list.size() - 1; i++) {
for (int j = list.size() - 1; j > i; j--) {
if(list.get(j).toString().equals(list.get(i).toString())){
list.remove(j);
}
}
}
System.out.println(list);
}
}

结果:

[Book [bookId=1001], Book [bookId=1002], Book [bookId=1003], Book [bookId=1003]]

[Book [bookId=1001], Book [bookId=1002], Book [bookId=1003]]