java中的Comparable接口的使用

不念不忘少年蓝@ 2023-07-18 06:51 14阅读 0赞

1、Comparable接口中的唯一的方法是：  
public static final int compareTo(object o);  
(1)当this.value==o.value（本来的数与参数相比较）时，返回0；  
(2)当this.value>o.value时，返回正数  
(3)当this.value<o.value时，返回负数  
2.Comparable接口的作用  
（1）它可以使继承他的类进行比较大小，只需要调用实现类的compareTo方法即可  
（2）如果我们想要排序一个自定义类，或者让一个自定义类可以比较大小就需要实现Comparable接口。  
（3）当需要排序的集合或数组不是单纯的数字型时，通常可以Comparable

## 代码实现如下 ##

import java.util.Date;
    
    public class Student  implements Comparable<Student> {
        
    
    	private String sid;
    	private String name;
    @Override
    	public String toString() {
        
    		return "Student [name=" + name + ", sid=" + sid + "]";
    	}
    	public String getName() {
        
    		return name;
    	}
    	public void setName(String name) {
        
    		this.name = name;
    	}
    	public String getSid() {
        
    		return sid;
    	}
    	public void setSid(String sid) {
        
    		this.sid = sid;
    	}
    public Student(String name, String sid) {
        
    	super();
    	this.name = name;
    	this.sid = sid;
    }
    public Student() {
        
    	super();
    }
    	@Override
    	public int compareTo(Student o) {
        
    	
    		return this.sid.compareTo(o.sid);
    	}
    
    }

import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.Collections;
    
    public class TestComparable {
        
    
    	public static void main(String[] args) {
        
    		// TODO Auto-generated method stub
         Student stu1 = new Student("曹邹","49");
         Student stu2 = new Student("张敏","15");
         Student stu3 = new Student("赵华","26");
         Student stu4 = new Student("铁花","10");
         Student stu5 = new Student("孙静","97");
         
         {
        
        	 //测试数组对象排序
        	 Student[] students = new Student[5];
        	 students[0]=stu1;
        	 students[1]=stu2;
        	 students[2]=stu3;
        	 students[3]=stu4;
        	 students[4]=stu5;
        	 System.out.println("数组排序前："+Arrays.toString(students));
        	 System.out.println();
        	 Arrays.sort(students);
        	 System.out.println("数组升序排序后："+Arrays.toString(students));
        	 System.out.println();
        	 Arrays.sort(students,Collections.reverseOrder());
        	 System.out.println("数组逆序后："+Arrays.toString(students));
         }
         {
        
        	 //测试ArrayList列表对象排序
        	 ArrayList<Student> studentArrayList = new ArrayList<Student>();
        	 studentArrayList.add(stu1);
        	 studentArrayList.add(stu2);
        	 studentArrayList.add(stu3);
        	 studentArrayList.add(stu4);
        	 studentArrayList.add(stu5);
        	 System.out.println();
        	 System.out.println("ArrayList列表排序前："+studentArrayList);
        	 Collections.sort(studentArrayList);
        	 System.out.println();
        	 System.out.println("ArrayList升序排序后："+studentArrayList);
        	 System.out.println();
        	 Collections.sort(studentArrayList,Collections.reverseOrder());
        	 System.out.println("ArrayList列表逆序排序后："+studentArrayList);
         }
    	}
      Student a=new Student();
     
    }

## 代码运行结果 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTcyMzAwMw_size_16_color_FFFFFF_t_70]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTcyMzAwMw_size_16_color_FFFFFF_t_70]: /images/20230528/7f58665fbc1e4283b55f6975abad9125.png