java 对象String类型属性排序

方法一：内部类实现comparator接口

代码演示

import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

class B{
	String name;
	String date;
}
public class Test {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		B a [] = new B[n]; //声明一个对象数组
		for (int i = 0; i < n; i++) {
			a[i] = new B(); //分配内存等操作
			a[i].name = in.next();
			a[i].date = in.next();
		}
		//从小到大大排序
		Arrays.sort(a, new Comparator<B>() { //内部类

			@Override
			public int compare(B o1, B o2) {
				return o1.date.compareTo(o2.date);
			}
			
		});
		
		for (int i = 0; i < n; i++) { //输出
			System.out.print(a[i].name+" ");
			System.out.println(a[i].date);
		}
	}
}

输入

5
John 2001/05/12
Tom 1814/09/06
Ann 2121/01/30
James 1814/09/05
Steve 1967/11/20

结果

James 1814/09/05
Tom 1814/09/06
Steve 1967/11/20
John 2001/05/12
Ann 2121/01/30

方法二：实现comparable接口

代码演示

import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

class A implements Comparable<A>{ //实现comparable接口，复写comparato方法
	String name;
	String date;
	@Override
	public int compareTo(A a) { 
		if (this.date.compareTo(a.date) == -1) 
			return 1;
		else 
			return -1;
	}
}
public class Test {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		A a [] = new A[n];
		for (int i = 0; i < n; i++) {
			a[i] = new A();
			a[i].name = in.next();
			a[i].date = in.next();
		}
		Arrays.sort(a);//从大到小排序
		
		for (int i = 0; i < n; i++) {
			System.out.print(a[i].name+" ");
			System.out.println(a[i].date);
		}
	}
}

输入

5
John 2001/05/12
Tom 1814/09/06
Ann 2121/01/30
James 1814/09/05
Steve 1967/11/20

结果

Ann 2121/01/30
John 2001/05/12
Steve 1967/11/20
Tom 1814/09/06
James 1814/09/05