今天在做專案時，需要根據序號排序，然而序號是在java中通過邏輯處理賦值的並不是直接在sql中通過order by 解決的；而ArrayList沒有實現Comparable介面，不能實現按需要排序；

<span style="font-family:Microsoft YaHei;">import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class StudentSort implements Comparable<Object> {
	
	private int id;
	
	private String name;

	public StudentSort(int id,String name) {
		this.id=id;
		this.name=name;
	}
	
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	@Override
	public int compareTo(Object o) {
		StudentSort student = (StudentSort)o;
		int id1 = student.getId();
		int id2 = this.getId();
		return id2>id1?1:-1;
	}
	
	public static void main(String[] args) {
		StudentSort s1 = new StudentSort(2, "xue");
		StudentSort s2 = new StudentSort(1,"yang");
		StudentSort s3 = new StudentSort(3,"feng");
		List<StudentSort> list = new ArrayList<StudentSort>();
		list.add(s3);
		list.add(s1);
		list.add(s2);
		/* 按照id升級排序
		 * */
		Collections.sort(list);
		for (StudentSort studentSort : list) {
			System.out.println(studentSort.getId()+":"+studentSort.getName());
		}
	}
	
}</span>