使用java8, 排序

我就是我 2022-06-05 08:17 149阅读 0赞

package com.demo;
    
    public class Student {
    
    	private String id;
    
    	public String getId() {
    		return id;
    	}
    
    	public void setId(String id) {
    		this.id = id;
    	}
    
    	@Override
    	public String toString() {
    		return "Student [id=" + this.getId() + "]";
    	}
    
    }

1.给单个属性排序

package com.demo;
    
    import java.util.ArrayList;
    import java.util.Comparator;
    import java.util.List;
    import java.util.stream.Collectors;
    
    
    public class Test {
    
    	public static void main(String[] args) {
    		List<Student> stuList = new ArrayList<Student>();
    		Student s1 = new Student();
    		s1.setId("3345");
    		Student s2 = new Student();
    		s2.setId("12454");
    		Student s3 = new Student();
    		s3.setId("23");
    		stuList.add(s1);
    		stuList.add(s2);
    		stuList.add(s3);
    		//1.sort
    		stuList.sort((a,b)->a.getId().compareTo(b.getId()));
    		stuList.forEach(s -> System.out.println(s.toString()));
    		//2.sorted
    //		List<Student> newList1 = stuList.stream().sorted(Comparator.comparing(Student::getId))
    //                .collect(Collectors.toList());
    //		newList1.forEach(s -> System.out.println(s.toString()));
    		//3.sorted 倒序
    //		List<Student> newList2 = stuList.stream().sorted(Comparator.comparing(Student::getId).reversed())
    //                .collect(Collectors.toList());
    //		newList2.forEach(s -> System.out.println(s.toString()));
    		//3.给list基本数据排序
    //		List<String> strList = Arrays.asList("234","123","87","43");
    //		Collections.sort(strList);
    //		strList.forEach(e -> System.out.println(e));
    		
    	}
    }

2.给多个属性排序

package com.demo;
    
    import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.Collections;
    import java.util.Comparator;
    import java.util.List;
    import java.util.stream.Collectors;
    
    
    public class Test {
    
    	public static void main(String[] args) {
    		List<Student> stuList = new ArrayList<Student>();
    		Student s1 = new Student("222", "zhangsan");
    		Student s2 = new Student("111", "wanger");
    		Student s3 = new Student("222", "lishi");
    		stuList.add(s1);
    		stuList.add(s2);
    		stuList.add(s3);
    		//1.直接使用sort(多属性比较)
    		stuList.sort(Comparator.comparing(Student::getId).thenComparing(Student::getName));
    		stuList.forEach(System.out::println);
    		
    		//2.构建比较器(多属性比较)
    		Comparator<Student> c = (p, o) -> p.getId().compareTo(o.getId());
    		c = c.thenComparing((p, o) -> p.getName().compareTo(o.getName()));
    		stuList.sort(c);
    		stuList.forEach(s -> System.out.println(s.toString()));
    		
    		//1.sort(单属性比较)
    		stuList.sort((a,b)->a.getId().compareTo(b.getId()));
    		stuList.forEach(s -> System.out.println(s.toString()));
    		
    		//2.sorted(单属性比较)
    		List<Student> newList1 = stuList.stream().sorted(Comparator.comparing(Student::getId))
                    .collect(Collectors.toList());
    		newList1.forEach(s -> System.out.println(s.toString()));
    		
    		//3.sorted 倒序
    		List<Student> newList2 = stuList.stream().sorted(Comparator.comparing(Student::getId).reversed())
                    .collect(Collectors.toList());
    		newList2.forEach(s -> System.out.println(s.toString()));
    		
    		//4.给list基本数据排序
    		List<String> strList = Arrays.asList("234","123","87","43");
    		Collections.sort(strList);
    		strList.forEach(e -> System.out.println(e));
    		
    	}
    }

ps：如果想倒序，只要将p和o反过来即可