TreeSet集合排序方式二:定制排序Comparator
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TreeSet集合排序方式二:定制排序Comparator
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Comparator有兩種實現方式:
1,匿名內部類
2,創建一個類用于實現Comparator,該類創建的對象就是比較器
Person類
public class Person implements Comparable<Person> {private String name;private String sex;private int age;private Book books;public String getName() {return name;}public void setName(String name) {this.name = name;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public Book getBooks() {return books;}public void setBooks(Book books) {this.books = books;}@Overridepublic String toString() {return "Person [name=" + name + ", sex=" + sex + ", age=" + age + ", books.name=" + books.getBookName() + ", books.price=" + books.getPrice() + "]";}public Person(String name, String sex, int age, Book books) {super();this.name = name;this.sex = sex;this.age = age;this.books = books;}public Person() {super();}}Book類
package Homework3;public class Book {//Book類中 有 書名,書的價格private String bookName;private int price;public String getBookName() {return bookName;}public void setBookName(String bookName) {this.bookName = bookName;}public int getPrice() {return price;}public void setPrice(int price) {this.price = price;}@Overridepublic String toString() {return "Book [bookName=" + bookName + ", price=" + price + "]";}public Book(String bookName, int price) {super();this.bookName = bookName;this.price = price;}public Book() {super();}}Comparator實現–匿名內部類
public class Test {public static void main(String[] args){//ComparatorTreeSet<Person> set2=new TreeSet<>(new Comparator<Person>() {@Overridepublic int compare(Person o1, Person o2) {if(o1.getAge()>o2.getAge()){return -1;}else if (o1.getAge()<o2.getAge()) {return 1;}else {CollationKey key=Collator.getInstance().getCollationKey(o1.getName());CollationKey key2=Collator.getInstance().getCollationKey(o2.getName());int n=key.compareTo(key2);if(n>0){return 1;}else if (n<0) {return -1;}else {int a=o1.getBooks().getPrice()-o2.getBooks().getPrice();if(a>0){return -1;}else if (a<0) {return 1;}else {CollationKey key3=Collator.getInstance().getCollationKey(o1.getBooks().getBookName());CollationKey key4=Collator.getInstance().getCollationKey(o2.getBooks().getBookName());int m=key3.compareTo(key4);if(m>0){return 1;}else if (m<0) {return -1;}else {return 0;}}}}}}); // 第一條件: 年齡 降序set2.add(new Person("Jane1", "female", 20, new Book("z指環王", 30)));set2.add(new Person("Jane2", "female", 30, new Book("z指環王", 30))); // 第二條件: 姓名升序set2.add(new Person("Ada3", "female", 30, new Book("z指環王", 30))); // 第三條件: 書的價格 降序set2.add(new Person("Ada4", "female", 30, new Book("z指環王", 50))); // 第四條件: 書名 升序set2.add(new Person("Ada5", "female", 30, new Book("m指環王", 50)));System.out.println(set2);} }總結
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