String performance optimization in Java _java

Instead of using string constructors, strings can be used directly.

Two special cases:

1) to convert char [] to a string,
(2) using a substring () method of a large string object;

String.Equals () is faster than string.equalsignorecase ();

Try to use StringBuilder to construct a string instead of the "+" operator and String.Concat () (unless it is an expression, String s = a + B + c);

StringBuilder is not synchronized (not synchronized), so it is faster than stringbuffer;

In string[buffer| Builder] constructor, because creating a buffer that is too small can degrade performance;

String.Length () ==0 is faster than String.Equals (""). Use Java 6 o'clock, string.isempty () faster;

Calling String.tostring () is meaningless;

Because a string is immutable, all of the string's methods return a new instance by returning the modified string.

The String.Split (regex) actually simply invokes the Pattern.compile (Regex). Split (this, limit), and each compile () returns a new pattern. So if you call split frequently, it's best to create a single pattern instance and reuse it instead of split ().

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