StringBuilder sb = new StringBuilder(); for(int i=0;i<100;i++){ sb.insert(0, Integer.toString(i)); } Warning: It defeats the purpose of StringBuilder, but it does what you asked. Better technique (although still not ideal): Reverse each string you want to insert. Append each string to a StringBuilder. Reverse the entire StringBuilder when you’re done. This will turn an O(n²) solution … Read more
The simplest and most efficient way is to perform this command: data.Length–; by doing this you move the pointer (i.e. last index) back one character but you don’t change the mutability of the object. In fact, clearing a StringBuilder is best done with Length as well (but do actually use the Clear() method for clarity … Read more
Using the insert method with the position parameter set to 0 would be the same as prepending (i.e. inserting at the beginning). C# example : varStringBuilder.Insert(0, “someThing”); Java example : varStringBuilder.insert(0, “someThing”); It works both for C# and Java
NOTE: This answer was written when .NET 2.0 was the current version. This may no longer apply to later versions. String.Format uses a StringBuilder internally: public static string Format(IFormatProvider provider, string format, params object[] args) { if ((format == null) || (args == null)) { throw new ArgumentNullException((format == null) ? “format” : “args”); } … Read more
Mutability Difference: String is immutable, if you try to alter their values, another object gets created, whereas StringBuffer and StringBuilder are mutable so they can change their values. Thread-Safety Difference: The difference between StringBuffer and StringBuilder is that StringBuffer is thread-safe. So when the application needs to be run only in a single thread then … Read more
If you have to write code for Internet Explorer make sure you chose an implementation, which uses array joins. Concatenating strings with the + or += operator are extremely slow on IE. This is especially true for IE6. On modern browsers += is usually just as fast as array joins. When I have to do … Read more
It should be r.append(“\n”); But I recommend you to do as below, r.append(System.getProperty(“line.separator”)); System.getProperty(“line.separator”) gives you system-dependent newline in java. Also from Java 7 there’s a method that returns the value directly: System.lineSeparator()
Others have pointed out the deleteCharAt method, but here’s another alternative approach: String prefix = “”; for (String serverId : serverIds) { sb.append(prefix); prefix = “,”; sb.append(serverId); } Alternatively, use the Joiner class from Guava 🙂 As of Java 8, StringJoiner is part of the standard JRE.
Two ways that work: Use stringBuilderObj.setLength(0). Allocate a new one with new StringBuilder() instead of clearing the buffer. Note that for performance-critical code paths, this approach can be significantly slower than the setLength-based approach (since a new object with a new buffer needs to be allocated, the old object becomes eligible for GC etc).
Version 1 is preferable because it is shorter and the compiler will in fact turn it into version 2 – no performance difference whatsoever. More importantly given we have only 3 properties it might not make a difference, but at what point do you switch from concat to builder? At the point where you’re concatenating … Read more