判断类的两个对象是否相同要重新实现equals方法

import java.util.Objects;

public class ObjectProperty {
    public String devId;
    public long timestamp;
    public double latitude;
    public double longitude;
    public int satellite;
    public double hdop;
    public double altitude;
    public double speed;
    public double direction;
    public ObjectProperty(String devId2, long timestamp2, double latitude2, double longitude2, int satellite2,
            double hdop2, double altitude2, double speed2, double direction2) {
        this.devId=devId2;this.timestamp=timestamp2;this.latitude=latitude2;this.longitude=longitude2;this.satellite=satellite2;this.hdop=hdop2;this.altitude=altitude2;this.speed=speed2;this.direction=direction2;
    }
    public String getDevId() {
        return devId;
    }
    public void setDevId(String devId) {
        this.devId = devId;
    }
    public long getTimestamp() {
        return timestamp;
    }
    public void setTimestamp(long timestamp) {
        this.timestamp = timestamp;
    }
    public double getLatitude() {
        return latitude;
    }
    public void setLatitude(double latitude) {
        this.latitude = latitude;
    }
    public double getLongitude() {
        return longitude;
    }
    public void setLongitude(double longitude) {
        this.longitude = longitude;
    }
    public int getSatellite() {
        return satellite;
    }
    public void setSatellite(int satellite) {
        this.satellite = satellite;
    }
    public double getHdop() {
        return hdop;
    }
    public void setHdop(double hdop) {
        this.hdop = hdop;
    }
    public double getAltitude() {
        return altitude;
    }
    public void setAltitude(double altitude) {
        this.altitude = altitude;
    }
    public double getSpeed() {
        return speed;
    }
    public void setSpeed(double speed) {
        this.speed = speed;
    }
    public double getDirection() {
        return direction;
    }
    public void setDirection(double direction) {
        this.direction = direction;
    }
    @Override
    public String toString() {
        return "ObjectProperty [devId=" + devId + ", timestamp=" + timestamp + ", latitude=" + latitude + ", longitude="
                + longitude + ", satellite=" + satellite + ", hdop=" + hdop + ", altitude=" + altitude + ", speed="
                + speed + ", direction=" + direction + "]";
    }
    /**
     * 判断两个对象时候相等必须重写这个方法
     */
    @Override
    public boolean equals(Object obj) {
        if(this==obj)
            return true;
        if(obj==null||getClass()!=obj.getClass())
            return false;
        ObjectProperty objectProperty=(ObjectProperty) obj;
        return Objects.equals(devId, objectProperty.devId)&&
                Objects.equals(timestamp, objectProperty.timestamp)&&
                Objects.equals(latitude, objectProperty.latitude)&&
                Objects.equals(longitude, objectProperty.longitude)&&
                Objects.equals(satellite, objectProperty.satellite)&&
                Objects.equals(hdop, objectProperty.hdop)&&
                Objects.equals(altitude, objectProperty.altitude)&&
                Objects.equals(speed, objectProperty.speed)&&
                Objects.equals(direction, objectProperty.direction);
        //return super.equals(obj);
    }
    @Override
    public int hashCode() {
        return this.devId.hashCode();
        //return super.hashCode();
    }
    
}

首先如果是同一个对象那么就返回真

如果不是同一个类绝对为假

如果两个对象的所有关注的属性全部相同那么可以两个对象相同

另外hashcode的简单覆盖是直接返回唯一id的hashcode而不是类的hashcode那么如果唯一的id是相同的话，可以认为两个对象的Hashcode相同时同一个对象