如何根据属性比较来自相同 class 的对象？

Question

我有这个对象：

COSTOS Costos = new COSTOS(1781, 359.13, "BISAG.SUP.PUER.TRA.I", "67550T9AT00ZZ");
        COSTOS Herramienta = new COSTOS(1795, 299.11, "BISAG.INF.PUER.TRA.I", "67960T2MT02ZZ");

这是我的 class:

public class COSTOS implements Comparable<COSTOS>{

    public int referencia;
    public double monto;
    public String descripcion;
    public String NumeroParte;

    //Constructor


    //getters setters

另外，我实现了 HashCode 和 equals：

@Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((NumeroParte == null) ? 0 : NumeroParte.hashCode());
        result = prime * result + ((descripcion == null) ? 0 : descripcion.hashCode());
        long temp;
        temp = Double.doubleToLongBits(monto);
        result = prime * result + (int) (temp ^ (temp >>> 32));
        result = prime * result + referencia;
        return result;
    }
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        COSTOS other = (COSTOS) obj;
        if (NumeroParte == null) {
            if (other.NumeroParte != null)
                return false;
        } else if (!NumeroParte.equals(other.NumeroParte))
            return false;
        if (descripcion == null) {
            if (other.descripcion != null)
                return false;
        } else if (!descripcion.equals(other.descripcion))
            return false;
        if (Double.doubleToLongBits(monto) != Double.doubleToLongBits(other.monto))
            return false;
        if (referencia != other.referencia)
            return false;
        return true;
    }

How could i implement a method that could print all the attributes that are not equals?

我尝试使用 "import java.util.Objects;" 来使用："Objects.hash(referencia, monto, descripcion, NumeroParte);"，这样可能会给我打印结果

Answer 1

如果我理解你的需求是正确的，你想打印出两个对象中不相同的属性值，那么你可以创建一个方法如下。

public void compareAttributes(COSTOS other) {
    if (this.getMonto() != other.getMonto()) {
       System.out.println("Not equal. This obj : " + this.getMonto() 
                        + " Other obj : " + other.getMonto());
    }

    // you can do the same for the remaining attributes.
}

编辑：

正如@Andreas 在评论中指出的那样，您应该将此方法放在 COSTOS class 本身中，以便可以轻松比较每个对象。

Answer 2

首先，可以使用 Java 7:

中添加的空安全 Objects 辅助方法来简化您的方法

@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + Objects.hashCode(this.NumeroParte);
    result = prime * result + Objects.hashCode(this.descripcion);
    result = prime * result + Double.hashCode(this.monto);
    result = prime * result + this.referencia;
    return result;
}

@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null || getClass() != obj.getClass())
        return false;
    COSTOS other = (COSTOS) obj;
    return (Objects.equals(this.NumeroParte, other.NumeroParte)
         && Objects.equals(this.descripcion, other.descripcion)
         && Double.doubleToLongBits(this.monto) == Double.doubleToLongBits(other.monto)
         && this.referencia == other.referencia);
}

How could i implement a method that could print all the attributes that are not equals?

要打印差异，请执行与 equals 方法相同的比较：

public void printDifferences(COSTOS other) {
    if (! Objects.equals(this.NumeroParte, other.NumeroParte))
        System.out.println("Different NumeroParte: " + this.NumeroParte + " != " + other.NumeroParte);
    if (! Objects.equals(this.descripcion, other.descripcion))
        System.out.println("Different descripcion: " + this.descripcion + " != " + other.descripcion);
    if (Double.doubleToLongBits(this.monto) != Double.doubleToLongBits(other.monto))
        System.out.println("Different monto: " + this.monto + " != " + other.monto);
    if (this.referencia != other.referencia)
        System.out.println("Different referencia: " + this.referencia + " != " + other.referencia);
}

如何根据属性比较来自相同 class 的对象？

How to compare objects from a same class based on their attributes?

java

equals

hashcode