java - 实现compareObjects()的正确方法是什么

Question

我的compareObjects方法实现如下

public static int compareObjects(Comparable a, Comparable b){

        if (a == null && b == null){
            return 0;
        } else if (a == null && b != null){
            return -1;
        } else if (a != null && b == null){
            return 1;
        } else {
            return a.compareTo(b);
        }
    }

当我通过 findBugs 运行此命令时，我在 return a.compareTo(b) 行上收到此建议:

There is a branch of statement that, if executed, guarantees that a null value will be dereferenced, which would generate a NullPointerException when the code is executed. Of course, the problem might be that the branch or statement is infeasible and that the null pointer exception can't ever be executed; deciding that is beyond the ability of FindBugs. Due to the fact that this value had been previously tested for nullness, this is a definite possibility.

此时a永远不可能为空。为什么 FindBugs 向我显示此建议？我该如何纠正这个问题？实现compareObjects()的正确方法是什么？

Answer 1

我认为这可能是因为您不需要额外的 && 语句。在第一个 if 语句之后，您已经知道其中一个为 null。

public static int compareObjects(Comparable a, Comparable b){

    if (a == null && b == null){
        return 0;
    } else if (a == null){
        return -1;
    } else if (b == null){
        return 1;
    } else {
        return a.compareTo(b);
    }
}