Java中實作對象的比較

Java中通過接口實作兩個對象的比較，首先類要實作comparable接口，使用泛型規定了要進行比較的對象所屬的類，而comparable接口的實作必須要定義的方法則是compareTo方法，在方法中傳入此類的另一個對象，通過標明的成員變量與之比較，如果大于則傳回1，小于傳回-1，相等傳回0.

例子代碼：

package com.study.write;import java.util.*;

public class EmployeeSortTest {

public static void main(String[] args) {

Employee2[] staff = new Employee2[3];

staff[0] = new Employee2("Harry", 35000);

staff[1] = new Employee2("Danny", 40000);

staff[2] = new Employee2("Tony", 20000);

Arrays.sort(staff);

//print out information about all Employee objects

for(Employee2 e:staff)

System.out.println("name = " + e.getName() +" " + "salary = " + e.getSalary());

}

}

class Employee2 implements Comparable<Employee2> {

public Employee2(String n, double s) {

name = n;

salary = s;

public String getName() {

return name;

public double getSalary() {

return salary;

public void raiseSalary(double byPecent) {

double raise = salary * byPecent / 100;

salary += raise;

/**compares employees by salary

@param other another Employee object

@return a negative value if this employee has a lower

salary than otherObject, 0 if the salaries are the same,

a positive value otherwise

*/

public int compareTo(Employee2 other) {

if(salary < other.salary) return -1;

if(salary > other.salary) return 1;

return 0;

private String name;

private double salary;

運作結果為：