声纳空指针冲突

Question

Sonar giving below null pointer violations for below line

existed.keySet()

Please could you help us to resolve this issue.

    private boolean isEqualCaptions(Map<String, String> existed, Map<String, String> updated) {

        if(existed == null && updated != null) return false;
        if(existed != null && updated == null) return false;
        for(String key:existed.keySet()){
            if(existed.get(key).compareTo(updated.get(key)) != 0) return false;
        }
    return true;
}

Answer 1

If existed and updated are both null , then the program will reach the loop, and existed.keySet() will throw a NullPointerException , that's why you get the warning.

Before the loop, you should add a condition to make sure existed is not null .

private boolean isEqualCaptions(Map<String, String> existed, Map<String, String> updated) {
    if (existed == null && updated != null) return false;
    if (existed != null && updated == null) return false;
    if (existed != null) {
        for (String key : existed.keySet()) {
            if (existed.get(key).compareTo(updated.get(key)) != 0) return false;
        }
    }
    return true;
}

Finally, the condition A && !B || !A && B A && !B || !A && B can be simplified using the XOR operator as A ^ B , so the first two if statements can be combined and simplified:

private boolean isEqualCaptions(Map<String, String> existed, Map<String, String> updated) {
    if (existed == null ^ updated == null) return false;
    if (existed != null) {
        for (String key : existed.keySet()) {
            if (existed.get(key).compareTo(updated.get(key)) != 0) return false;
        }
    }
    return true;
}