Java naming conventions must be followed for all type names.

As per the conventions, all type (class, enum, interface) names in Java must begin with an uppercase letter. Not following this convention would make it harder to search for such type declarations in large source files.

Bad Practice

Avoid typenames that start with a lowercase letter.

class klass {
    //..rest of the code
}

Recommended

Consider following the conventions when naming your types.

class Klass {
    //..rest of the code
}

References

Oracle - Java naming conventions

GooseterV / Project-Euler

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