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in Technique[技术] by (71.8m points)

java - How to write for loop that returns string with java8 features?

Basically what I want to do is to write a for loop like below with java 8 features,

private String createHashCode() {
    for (int i = 0; i < MAX_TRY; i++) {
        final String hashCode = createRandomString();
        if (!ishashCodeExistence(hashCode)) {
            return hashCode;
        }
    }
    throw new HashCodeCollisonException();
}

what I tried is ;

private String createHashCode() {
    IntStream.range(0, MAX_TRY).forEach($ -> {
        final String hashCode = createRandomString();
        if (!ishashCodeExistence(hashCode)) {
            return hashCode;
        }
    });
    throw new HashCodeCollisonException();
}

However, foreach method in lambda returns void so that I cannot return a string.

Is there any way to write my method instead of using normal for loop?


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by (71.8m points)

Here's how you could rewrite it with a stream if you really wanted to, although I personally prefer the good old for loop in this specific case:

private String createHashCode() {
    return IntStream
            .range(0, MAX_TRY)
            .mapToObj(x -> createRandomString())
            .filter(hashCode -> !ishashCodeExistence(hashCode))
            .findFirst()
            .orElseThrow(HashCodeCollisonException::new);
}

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