Findbug告诉我，我没有明显的理由将非负值与-1进行比较。

Question

我有这样的代码，它在FindBugs中显示了以下错误：

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Bug: Bad comparison of nonnegative value with -1 in hydra.extensions.drivers.eg2.internal.EG2GatewaySimulator$1.run()

This code compares a value that is guaranteed to be non-negative with a negative constant or zero. 

Rank: Scary (5), confidence: High
Pattern: INT_BAD_COMPARISON_WITH_NONNEGATIVE_VALUE 
Type: INT, Category: CORRECTNESS (Correctness)

关于守则：

String receivedMessage = "";
char c;
boolean isValidChar;
do {
    c = (char) in.read();
    isValidChar = (c != '\r') && (c != -1);
    if (isValidChar) {
        receivedMessage += c;
    }
} while (isValidChar);

Answer 1

字符值为16位，非负值：

char: char数据类型是单个16位Unicode字符.它的最小值为'\u0000‘(或0)，最大值为'\uffff’(含65,535 )。

你在把它和-1比较。