public class AgeComparator implements Comparator 
{
public int compare(Object op1, Object op2) {
Employee eOp1 = (Employee) op1; Employee eOp2 = (Employee) op2; // 按年龄排序 return eOp1.getAge()-(eOp2.getAge());
}
}
public class NameComparator implements Comparator { public int compare(Object op1, Object op2) { Employee eOp1 = (Employee) op1; Employee eOp2 = (Employee) op2; // 按姓名排序 return eOp1.getName().compareTo(eOp2.getName()); }}public class SalaryComparator implements Comparator { public int compare(Object op1, Object op2) { Employee eOp1 = (Employee) op1; Employee eOp2 = (Employee) op2; // 按薪水排序 return eOp1.getSalary()-(eOp2.getSalary()); }}Employee类：
public class Employee{ protected String name; protected int age; protected int salary; public Employee(String name,int age,int salary){ this.name=name; this.age=age; this.salary=salary; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getSalary() { return salary; } public void setSalary(int salary) { this.salary = salary; } }测试：
public class Main{ public static void main(String[] args){ List<Employee> employees=new ArrayList<Employee>(); employees.add(new Employee("Andy",21,2000)); employees.add(new Employee("Felix",21,3000)); employees.add(new Employee("Bill",35,20000)); employees.add(new Employee("Helen",21,10000)); employees.add(new Employee("Cindy",28,8000)); employees.add(new Employee("Douglas",25,5000)); // 按名称排序 Collections.sort(employees,new NameComparator()); display(employees); // 按年龄排序 Collections.sort(employees,new AgeComparator()); display(employees); // 按薪水排序 Collections.sort(employees,new SalaryComparator()); display(employees); } public static void display(List<Employee> employees){ for(Employee e:employees){ System.out.println("雇员名="+e.getName()+" 年龄="+e.age+" 薪水="+e.getSalary()); } System.out.println(); }}输出：
雇员名=Andy 年龄=21 薪水=2000雇员名=Bill 年龄=35 薪水=20000雇员名=Cindy 年龄=28 薪水=8000雇员名=Douglas 年龄=25 薪水=5000雇员名=Felix 年龄=21 薪水=3000雇员名=Helen 年龄=21 薪水=10000雇员名=Andy 年龄=21 薪水=2000雇员名=Felix 年龄=21 薪水=3000雇员名=Helen 年龄=21 薪水=10000雇员名=Douglas 年龄=25 薪水=5000雇员名=Cindy 年龄=28 薪水=8000雇员名=Bill 年龄=35 薪水=20000雇员名=Andy 年龄=21 薪水=2000雇员名=Felix 年龄=21 薪水=3000雇员名=Douglas 年龄=25 薪水=5000雇员名=Cindy 年龄=28 薪水=8000雇员名=Helen 年龄=21 薪水=10000雇员名=Bill 年龄=35 薪水=20000