java 哈希码和等于

Question

为以下 class 创建 hashCode 和 equals 方法。

private static class MyOb {

    private String name;
    private Integer quality;
    private final int MAXIMUM = 23;

}

我无法解决这个问题

Answer 1

Javaclass有默认的hashCode和通过superclass实现的equals方法方法。如果你想超越他们，你可以通过以下方式：

class MyOb {

private String name;
private Integer quality;
private final int MAXIMUM = 23;

@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((name == null) ? 0 : name.hashCode());
    result = prime * result + ((quality == null) ? 0 : quality.hashCode());
    return result;
}
@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    MyOb other = (MyOb) obj;
    if (name == null) {
        if (other.name != null)
            return false;
    } else if (!name.equals(other.name))
        return false;
    if (quality == null) {
        if (other.quality != null)
            return false;
    } else if (!quality.equals(other.quality))
        return false;
    return true;
}

}

注意：class不能是私有的或静态的

Answer 2

如果您想查看 class 的哈希码。创建对象

    Myob myObject=new Myob();
    System.out.println(myObject);

如果要等于方法

    myObject.equals(which one you want to campare);

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