Java String best practice regarding pool

I have always wondered what the most effective way is of creating String's in Java. By this I mean strings that won't change in value.

Example:

String prefix = "Hi, I am ";

The prefix won't change but the postfix might.

• I don't want to make the prefix a static final variable as it will always stay alive in the JVM even if the class is rarely used...bla bla.

• and when I do the following:

  String fullWord = ("Hi, I am "+_postFix);

  开发者_JAVA技巧I am guessing that the "Hi, I am" String value will remain in the Java String pool and I don't have the "overhead" of declaring the prefix as a variable.

Meaning my question boils down to this:

1. Will the Java String pool always be used when and when I don't declare a String variable using the new keyword?

2. Is it better to declare a String as a variable before using it?

3. How does the String pool work? Does the JVM detect that a same String value is often used and keeps referring to that String in JVM memory?

1. All literal Strings are interned.
2. Write code that is easy to understand. It really is not worth trying to nano-optimise this.
3. All literal Strings loaded by class loaders are interned, as are Strings returned by String.intern (which is a slow way of doing it, in typical implementations).