Trim a string based on the string length

Unicode handling

If your string contains special Unicode characters such as emojis, consider surrogate pairs. They take space like two people in a single seat, but are considered as one unit. So, use Code-Point-based length and substring methods:

String trimUnicodeString(String str, int max) {
    int[] codePoints = str.codePoints().toArray();
    int endIndex = Math.min(codePoints.length, max);
    StringBuilder builder = new StringBuilder();
    for(int i = 0; i < endIndex; i++) {
        builder.appendCodePoint(codePoints[i]);
    }
    return builder.toString();  // Trimming like a boss
}
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Harnessing Apache Commons

Apache Commons Lang provides you the StringUtils class, the Swiss army knife for string manipulations. It handles trimming elegantly and also appends an ellipsis if the string exceeds the maximum length:

String abbreviated = StringUtils.abbreviate("Exciting Java Code!", 10);
// Output: "Excitin..."
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Visualization

Imagine a tunnel 🎢 that can only accommodate a certain number of 🚂 train cars. If the train is too lengthy, the extra cars are simply left behind. This is the principle we apply when trimming a string:

String: "ChooChooTrainIsLong"
Length: 10

Tunnel: 🎢
Train:  🚂🚃🚃🚃🚃🚃🚃🚃🚃🚃...🚃🚃

Post trimming:

Before: 🚂🚃🚃🚃🚃🚃🚃🚃🚃🚃...🚃🚃 (Lengthy Train)
After:  🚂🚃🚃🚃🚃🚃🚃🚃🚃🚃 (Just Right)

Result: "ChooChooTr"

Trimming a string = Ensuring the train (string) fits perfectly into the tunnel (desired length)! 🎢🚂✂️

Advanced string handling mechanisms

Dealing with surrogate pairs

Remember, surrogate pairs in Unicode have their own space requirements. Use the correct length methods to avoid splicing characters:

int correctLength(String str) {
    // No more shabby trimmings 
    return str.codePointCount(0, str.length());
}

boolean isSafeToTrim(String str, int index) {
    // Is it safe to go under the knife?
    return !Character.isLowSurrogate(str.charAt(index));
}
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Semantic integrity through smart trimming

Be careful you don't end up distorting the meaning of a sentence or a term by trimming. Always consider the context:

String safeTrimming(String str, int max) {
    // Losing weight without losing meaning
    return (str.length() <= max || isSafeToTrim(str, max)) ? str : str.substring(0, max) + "…";
}
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Reusable trimming with static methods

Refactor trimming logic into a static method to reuse it conveniently:

public static String reusableTrimMethod(String str, int max) {
    // Reusable? You bet your braces!
    // Apply logic depending on the string features and context
}
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Maximizing efficiency in string manipulation

In-place operations for preserving resources

Preserve system resources by ensuring that you don't create a new string if trimming is unnecessary:

String efficientTrimming(String str, int max) {
    // No new strings. We recycle here!
    return str.length() > max ? str.substring(0, max) : str;
}
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Testing for exceptions/edge cases

Expect the unexpected - always test with edge cases like empty strings, strings precisely at the length limit:

String edgeCase = "";
String efficientTrimming = trimToLength(edgeCase, 10);  // No crash!
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StringUtils convenience

The StringUtils class from Apache Commons can treat nulls gracefully and provide efficient checks for empty or blank strings:

String safeAbbreviate = StringUtils.abbreviate("  ", 10);
// Result would be "  " because StringUtils handles blanks effortlessly
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