javaLogic errorEasy

String substring endIndex out of bounds exception

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What it should do

Extract at most first 5 characters of string. Example: extractPrefixSafely("abc") -> "abc"

What happens instead

java.lang.StringIndexOutOfBoundsException: String index out of range: 5

public class Main {
    public static String extractPrefixSafely(String text) {
        // substring throws StringIndexOutOfBoundsException if endIndex > length
        return text.substring(0, 5);
    }

    public static void main(String[] args) {
        System.out.println(extractPrefixSafely("abc"));
    }
}

Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).

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This bug belongs to the logic errors pattern

The wrong operator, an inverted condition, a formula the right way round but backwards.

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public class Main { public static String extractPrefixSafely(String text) { // substring throws StringIndexOutOfBoundsException if endIndex > length return text.substring(0, 5); } public static void main(String[] args) { System.out.println(extractPrefixSafely("abc")); } }

String substring endIndex out of bounds exception

What it should do

What happens instead

More logic errors to practise

Seen this error in your own code?

String substring endIndex out of bounds exception

What it should do

What happens instead

More logic errors to practise

Seen this error in your own code?