java 集合对象两种排序接口Comparator，Comparable

短命女 2023-10-05 21:11 81阅读 0赞

#### 文章目录 ####

*   *  Comparator，Comparable区别
     *  实例说明
     *   *  实现Comparable接口
         *  实现 Comparator 接口
         *  测试sort()排序

### Comparator，Comparable区别 ###

1、Comparable接口里面的方法是 public int compareTo(T o); 在java.lang包下  
Comparator接口里面的方法是 int compare(T o1,T o2); 在java.util包下  
2、Comparable 是在集合内部定义的方法实现的排序，Comparator 是在集合外部实现的排序，  
详细区别参考 [https://blog.csdn.net/xiangyuenacha/article/details/84255353][https_blog.csdn.net_xiangyuenacha_article_details_84255353]

### 实例说明 ###

#### 实现Comparable接口 ####

Student.java

class Student implements Comparable<Student> {
        
    	private String name;
    	private Integer age;
    
    	public Student(String name, Integer age) {
        
    		super();
    		this.name = name;
    		this.age = age;
    	}
    
    	public String getName() {
        
    		return name;
    	}
    
    	public void setName(String name) {
        
    		this.name = name;
    	}
    
    	public Integer getAge() {
        
    		return age;
    	}
    
    	public void setAge(Integer age) {
        
    		this.age = age;
    	}
    	
    	// 年龄从小到大排序
    	@Override
    	public int compareTo(Student stu) {
        
    		return stu.age < age ? 1 : -1;
    	}
    }

#### 实现 Comparator 接口 ####

StudentComparator.java

class StudentComparator implements Comparator<Student> {
        
    	
    	// 学生年龄从大到小排序
    	@Override
    	public int compare(Student o1, Student o2) {
        
    		return o1.getAge() > o2.getAge() ? 1 : -1;
    	}
    }

#### 测试sort()排序 ####

TestSort.java

public class TestSort {
        
    	public static void main(String[] args) {
        
    		Student stu1 = new Student("张三", 20);
    		Student stu2 = new Student("李四", 23);
    		Student stu3 = new Student("王五", 10);
    		List<Student> list = new ArrayList<Student>();
    		list.add(stu1);
    		list.add(stu2);
    		list.add(stu3);
    
    		// Lambda 实现 Comparator 接口 重写 compare 方法
    		// Collections.sort(list, (Student s1, Student s2) -> (s1.compareTo(s2)));
    		
    		// StudentComparator  实现   Comparator 接口
    		// Collections.sort(list, new StudentComparator());
    		
    		// 匿名内部类 实现 Comparator 接口
    		Collections.sort(list, new Comparator<Student>() {
        
    
    			@Override
    			public int compare(Student o1, Student o2) {
        
    				// TODO Auto-generated method stub
    				return o1.getAge() > o2.getAge() ? 1 : -1;
    			}
    		});
    		
    		// Student  类实现   Comparable 接口 ，重写compareTo 方法
    		// Collections.sort(list);
    		
    		Iterator<Student> iter = list.iterator();
    		while (iter.hasNext()) {
        
    			Student stu = iter.next();
    			System.out.println(stu.getName() + "      " + stu.getAge());
    		}
    	}
    }

运行结果

王五 10  
张三 20  
李四 23

[https_blog.csdn.net_xiangyuenacha_article_details_84255353]: https://blog.csdn.net/xiangyuenacha/article/details/84255353?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522161501383116780262570424%2522%252C%2522scm%2522%253A%252220140713.130102334..%2522%257D&request_id=161501383116780262570424&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2~all~baidu_landing_v2~default-1-84255353.pc_search_result_hbase_insert&utm_term=Comparable%E5%92%8CComparator%E6%8E%A5%E5%8F%A3%E6%9C%89%E4%BB%80%E4%B9%88%E5%8C%BA%E5%88%AB