Java

泛型课堂练习题(韩顺平老师)

定义Employee类

（1）该类包含：private成员变量name，sal，birthday，其中birthday为MyDate类的对象；

（2）为每一个属性定义getter，setter方法；

（3）重写toString方法输出name，sal，birthday

（4）MyDate类包含：private成员变量year，month，year；并为每一个属性定义getter，setter方法；

（5）创建该类的3个对象，并把这些对象放入ArrayList集合中（ArrayList需使用泛型来定义），对集合中的元素进行排序，并遍历输；

排序方式：调用ArrayList的sort方法，传入Comparator对象[使用泛型]，先按照name排序，如果name相同，则按生日日期的先后排序。

Employee:

package ch05;

public class Employee {
	
	private String name;
	private double sal;//薪水
	private MyDate birthday;
	
	public Employee(String name, double sal, MyDate birthday) {
		this.name = name;
		this.sal = sal;
		this.birthday = birthday;
	}

	public String getName() {
		return name;
	}

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

	public double getSal() {
		return sal;
	}

	public void setSal(double sal) {
		this.sal = sal;
	}

	public MyDate getBirthday() {
		return birthday;
	}

	public void setBirthday(MyDate birthday) {
		this.birthday = birthday;
	}

	@Override
	public String toString() {
		return "nEmployee [name=" + name + ", sal=" + sal + ", birthday=" + birthday + "]";//  n换行
	}
	
	
	
	

}

 GenericExercise02:

package ch05;

import java.util.ArrayList;
import java.util.Comparator;

@SuppressWarnings({"all"})
public class GenericExercise02 {

	public static void main(String[] args) {
		
		ArrayListemployees = new ArrayList<>();
		employees.add(new Employee("tom", 20000, new MyDate(2000, 11, 11)));
		employees.add(new Employee("jack", 12000, new MyDate(2001, 12, 12)));
		employees.add(new Employee("hsp", 5000, new MyDate(1980, 10, 10)));
		
		System.out.println("employees=" + employees);
		
		
		employees.sort(new Comparator() {
			@Override
			public int compare(Employee emp1,Employee emp2) {
				if(!(emp1 instanceof Employee && emp2 instanceof Employee)) {
					System.out.println("类型不正确...");
					return 0;
				}
				int i = emp1.getName().compareTo(emp2.getName());
				if(i != 0) {
					return i;
				}
				return emp1.getBirthday().compareTo(emp2.getBirthday());
			}
		});
		
		System.out.println("==对雇员进行排序==");
		System.out.println(employees);
		

	}

}

MyDate:

package ch05;

public class MyDate implements Comparable{
	private int year;
	private int month;
	private int day;
	
	public MyDate(int year, int month, int day) {
		this.year = year;
		this.month = month;
		this.day = day;
	}

	public int getYear() {
		return year;
	}

	public void setYear(int year) {
		this.year = year;
	}

	public int getMonth() {
		return month;
	}

	public void setMonth(int month) {
		this.month = month;
	}

	public int getDay() {
		return day;
	}

	public void setDay(int day) {
		this.day = day;
	}

	@Override
	public String toString() {
		return "MyDate [year=" + year + ", month=" + month + ", day=" + day + "]";
	}
	
	@Override
	public int compareTo(MyDate o) {
		int yearMinus = year - o.getYear();
		if(yearMinus != 0) {
			return yearMinus;
		}
		int monthMinus = month - o.getMonth();
		if(monthMinus != 0) {
			return monthMinus;
		}
		return day - o.getDay();
	}
	

}