Removing the first 3 characters from a string

Short strings: Avoiding exceptions

What if your strings are shorter than 3 characters or empty? To avoid exceptions, use this method:

String shorten(String input) {
    return input.length() > 3 ? input.substring(3) : "";
}
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The method shorten("Hi") returns an empty string "". No more IndexOutOfBoundsException!

Large strings: Optimizing for performance

Working with long strings? Don't let performance suffer. Use the StringBuilder technique:

String longString = /* Think the length of "War and Peace" */;
StringBuilder sb = new StringBuilder(longString);
sb.delete(0, 3);
String result = sb.toString();
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This method provides significant efficient memory use for operations with large string values.

The Off-by-One Errors: Nipping them in the bud

Always ensure the right index value to prevent an off-by-one error, that sneaky bugger:

String sentence = "Bonjour";
String result = sentence.substring(3); // All good!
// result will be "jour"
String mistake = sentence.substring(2); // Oops! Off by one!
// mistake will be "njour" - an unintended French word
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Watch those indices! They start counting at zero folks.

Testing: Code's health check

Why not run some tests with a range of different inputs to ensure your code's working:

assertEquals("loWorld", "HelloWorld".substring(3)); // Hello to loWorld.
assertEquals("", "".substring(3)); // Houston, we have a problem. Will throw an exception, uh-oh!
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Design tests for both typical and edge cases. It's a bug-free life you want.

Handling exceptions: Keeping things in bounds

Error Proofs: Safeguarding the small and nothing

Add a safety net for less than 3 characters or null strings to keep those pesky exceptions at bay:

String safeSubstring(String str, int beginIndex) {
    if (str == null || str.length() <= beginIndex) {
        return "";
    }
    return str.substring(beginIndex);
}
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No more IndexOutOfBoundsException ruining your perfect runtime.

Versatile Code: One solution fits all

Remember, a good code is a reusable one. The function can be easily modified to remove any 'n' characters:

String removeChars(String str, int n) {
    return (str.length() > n) ? str.substring(n) : "";
}
// The same function can now remove the first 'n' characters. How cool is that?!
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This approach builds a maintainable and robust program that easily caters to future needs.