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JavaIntermediate#strings
JavaBeginner#strings
What is the difference between String, StringBuilder, and StringBuffer?
String is immutable. StringBuilder is mutable and not thread-safe (fast). StringBuffer is mutable and synchronized (thread-safe, slower). Use StringBuilder for single-threaded concatenation in loops.
Example
StringBuilder sb = new StringBuilder(); for (int i = 0; i < 5; i++) sb.append(i); System.out.println(sb.toString()); // "01234"