java - 为实现 Comparable 的泛型类创建一个 compareTo

Question

我有一个带有两个类型变量的通用类，它实现了 java.lang.Comparable。

public class DoubleKey<K,J> implements Comparable<DoubleKey<K,J>>{    private K key1;    private J key2;    public DoubleKey(K key1, J key2){        this.key1 = key1;        this.key2 = key2;    }     public K getFirstKey(){        return this.key1;    }    public J getSecondKey(){        return this.key2;    }    // need for Comparable interface    public int compareTo(DoubleKey<K,J> aThat){        ...    }}

因为我是用 Comparable 实现的，所以我需要编写 compareTo() 方法。因为 K, J 可以是 ANY 类型，所以我在如何完全比较它们方面遇到了问题。有没有办法在比较中捕获所有可能的类型(原始、包装、对象)？感谢您的帮助!

Answer 1

所以总结上面所说的并将其拼凑成一个工作代码是:

    public class DoubleKey<K extends Comparable<K>, J extends Comparable<J>>
        implements Comparable<DoubleKey<K, J>> {

    private K key1;
    private J key2;

    public DoubleKey(K key1, J key2) {
        this.key1 = key1;
        this.key2 = key2;
    }

    public K getFirstKey() {
        return this.key1;
    }

    public J getSecondKey() {
        return this.key2;
    }

    public int compareTo(DoubleKey<K, J> that) {

        int cmp = this.getFirstKey().compareTo(that.getFirstKey());
        if (cmp == 0)
            cmp = this.getSecondKey().compareTo(that.getSecondKey());
        return cmp;
    }
}