Java 练习(Object 练习一)

例子一

package com.klvchen.exer2;

public class OrderTest {
	public static void main(String[] args) {
		Order order1 = new Order(1001, "AA");
		Order order2 = new Order(1001, "BB");
		
		System.out.println(order1.equals(order2));  //false
		
		Order order3 = new Order(1001, "BB");
		System.out.println(order2.equals(order3));  //true
		
		String s1 = "BB";
		String s2 = "BB";
		System.out.println(s1 == s2);               //true
	}

}

class Order{
	private int orderId;
	private String orderName;
	
	public int getOrderId() {
		return orderId;
	}
	public void setOrderId(int orderId) {
		this.orderId = orderId;
	}
	public String getOrderName() {
		return orderName;
	}
	public void setOrderName(String orderName) {
		this.orderName = orderName;
	}
	
	public Order(int orderId, String orderName) {
		super();
		this.orderId = orderId;
		this.orderName = orderName;
	}
	
	@Override
	public boolean equals(Object obj) {
		if(this == obj) {
			return true;
		}
		
		if(obj instanceof Order) {
			Order order = (Order)obj;
			
			return this.orderId == order.orderId &&
					this.orderName.equals(order.orderName);
		}
		return false;
	}	
}

运行结果

例子二

请根据以下代码自行定义能满足需要的 MyDate 类,在MyDate类中覆盖equals方法，使其判断当两个MyDate类型对象的年月日都相同时，结果为true，否则为false。

MyDateTest.java

package com.klvchen.exer2;

public class MyDateTest {
	public static void main(String[] args) {
		MyDate m1 = new MyDate(14, 3, 1976);
		MyDate m2 = new MyDate(14, 3, 1976);
		
		if(m1 == m2) {
			System.out.println("m1 == m2");
		}else {
			System.out.println("m1 != m2"); //m1 != m2
		}
		
		if(m1.equals(m2)) {
			System.out.println("m1 is equal to m2");  //m1 is equal to m2

		} else {
			System.out.println("m1 is not equal to m2");
		}
	}

}


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

	public int getDay() {
		return day;
	}

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

	public int getMonth() {
		return month;
	}

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

	public int getYear() {
		return year;
	}

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

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		MyDate other = (MyDate) obj;
		if (day != other.day)
			return false;
		if (month != other.month)
			return false;
		if (year != other.year)
			return false;
		return true;
	}	
}

运行结果