package com.aff.equals;

public class TestOrder {

    public static void main(String[] args) {

        Order o1 = new Order(1001, "AA");

        Order o2 = new Order(1001, "AA");

        System.out.println(o1 == o2);// false

        System.out.println(o1.equals(o2));// false--->true  重写equals方法后

    }

}

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;

    }

    //比较两个order对象的属性是否完全相同，相同的话返回true

    public boolean equals(Object obj) {

        if (this == obj) {

            return true;

        } else if (obj instanceof Order) {

            Order o1 = (Order) obj;

            return this.orderId == o1.orderId && this.orderName.equals(o1.orderName);

        } else {

            return false;

        }

    }

}

输出结果：

false
true

package com.aff.equals;

public class TestMyDate {

    public static void main(String[] args) {

        MyDate m1 = new MyDate(12, 3, 2012);

        MyDate m2 = new MyDate(12, 3, 2012);

        if (m1 == m2) {

            System.out.println("m1==m2");

        } else {

            System.out.println("m1!=m2");

        }

        // boolean java.lang.Object.equals(Object obj)

        // 调用的为Object里面的equals方法，需要重写equals方法

        if (m1.equals(m2)) {

            System.out.println("m1 is equals 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;

    }

    //手动写的

    public boolean equals(Object obj) {

        if (this == obj) {

            return true;

        } else if (obj instanceof MyDate) {

            MyDate m = (MyDate) obj;

            return this.day == m.day && this.month == m.month && this.year == m.year;

        } else {

            return false;

        }

    }

}

输出结果：

m1!=m2
m1 is equals m2