声纳错误条件不应无条件地评估为“真”。或“假”； [英] Sonar error Conditions should not unconditionally evaluate to "TRUE" or to "FALSE"

问题描述

我正在违反声纳：

条件不应无条件地评估为 TRUE或 FALSE

"Conditions should not unconditionally evaluate to "TRUE" or to "FALSE""

以下代码。

List<MediaContent> savedList = source.getChildMediaContents();
List<MediaContent> supplierList = target.getChildMediaContents();

// if existing and incoming both empty
if(savedList == null && supplierList == null){
    return false;
}

// if one is null and other is not then update is required
if(savedList == null && supplierList != null){
    return true;
}

if(savedList != null && supplierList == null){
    return true;
}

在两个if块下面，它给出了错误

Below the two if blocks it is giving an error

// if one is null and other is not then update is required
if(savedList == null && supplierList != null){
    return true;
}

if(savedList != null && supplierList == null){
    return true;
}

推荐答案

if(savedList == null && supplierList == null){
    return false;
}

if(savedList == null && supplierList != null){

条件 supplierList！= null 始终为true。
由于Java中& 运算符的短路行为，在 supplierList之前的
！= null ，
savedList == null 必须先为真。

The condition supplierList != null is always true when reached. Due to the short-circuiting behavior of the && operator in Java, before supplierList != null is reached, savedList == null must be true first.

但是，如果 savedList == null 为true，则
则从上一个条件知道 supplierList 不是 null ，所以这是没有意义的条件。

But if savedList == null is true, then we know from the previous condition that supplierList is not null, so it's a pointless condition.

另一方面，如果 savedList = = null 为假，则
则由于短路行为，
supplierList！= null 不会

On the other hand, if savedList == null is false, then the due to the short-circuiting behavior, the supplierList != null will not be evaluated.

因此，无论 savedList == null 的结果如何，
supplierList！= null 永远不会被评估，
，因此您只需删除该条件即可。

Thus, regardless of the outcome of savedList == null, supplierList != null will never be evaluated, so you can simply remove that condition.

if (savedList == null) {
    return true;
}

下一步：

if(savedList != null && supplierList == null){

感谢之前的简化，现在很明显 savedList 不能为 null 。所以我们也可以删除该条件：

Thanks to the simplification earlier, now it's clear that savedList cannot be null. So we can remove that condition too:

if (supplierList == null) {
    return true;
}

简而言之，这等效于您发布的代码：

In short, this is equivalent to your posted code:

if (savedList == null && supplierList == null) {
    return false;
}

if (savedList == null || supplierList == null) {
    return true;
}

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