【java】toString和equals

public class Test {
    public static void main(String[] args){
        Time time = new Time(2022,4,27);
        System.out.println(time.toString());  //这里可以直接写System.out.println(time);

        Time t1 = new Time(2022,1,1);
        Time t2 = new Time(2022,1,1);
        System.out.println(t1.equals(t2)); //输出true

        Time t3 = new Time(2022,1,3);
        System.out.println(t2.equals(t3));  //输出false
    }
}

class Time{
    int year;
    int month;
    int day;
    public Time(){}
    public Time(int year,int month,int day){
        this.year = year;
        this.month = month;
        this .day = day;
    }
    public String toString(){
        return year +"年"+month +"月"+ day +"日";
    }

//改良版
public boolean equals(Object obj){
    if(obj == null || !(obj instanceof Time)){//如果obj为空 或者 obj不是Time，直接返回false
        return false;
    }
    if(this == obj){
        return true;
    }
    Time t = (Time)obj;  //这里直接转型，因为前面已经判断过obj了
    return this.year == t.year && this.month == t.month && this.day == t.day; //&&为短路与，全相等输出true，反之输出false
    }
}