In Java Is it efficient to use new String() instead of double quotes when string is really large and not using again?

Question

I have so many use cases where I have to initialize a large string and not use the same string anywhere else.

//Code-1
public class Engine{
public void run(){
    String q = "fjfjljkljflajlfjalkjdfkljaflkjdllllllllllllllsjfkjdaljdfkdjfnvnvnrrukvnfknv";
    //do something
   }
}

I call this run method very few times.

In Code-1 the string fjfjljkljflaj..... will get added to the string pool and will never get collected by GC. So I am thinking to initialize with the new operator.

//Code-2
public class Engine{
public void run(){
    String q = new String("fjfjljkljflajlfjalkjdfkljaflkjdllllllllllllllsjfkjdaljdfkdjfnvnvnrru");
    //do something
   }
}

Will 2nd code save some memory or there will be other factors to consider to decide which one is efficient?

This is micro-optimization; you don't need to do it. Just use the string in the usual way. — Robert Harvey, Jun 10 '21 at 11:27
It's not `q` that is added to the string pool, it is the string constant `"fjfjljklj..."`. Both versions contain this string constant and therefore the second approach is no improvement. — Thomas Kläger, Jun 10 '21 at 11:29
The string constant is still used in both cases and will still be added to the string pool in both cases. — Thomas Kläger, Jun 10 '21 at 11:37
@RobertHarvey it is not an optimization in any way, not even micro - case #2 just wastes memory — Gyro Gearless, Jun 10 '21 at 11:50
No. `new String("...")` with a string literal is practically never useful. Never use this, unless you have a very special reason. Just use the string literal instead. This does not help with garbage collection in any way. — Jesper, Jun 10 '21 at 12:31
@Jesper Is there any way to prevent literal strings from being added to the string pool. — shubham12511, Jun 10 '21 at 13:35
No, there is no way to prevent literal strings from being added to the string pool. — Jesper, Jun 10 '21 at 13:38
That’s one of the least relevant places for optimizations. — Holger, Jun 10 '21 at 16:31

score 0 · Answer 1 · answered Jul 29 '21 at 09:00

first thing -- if we create with the new String() object, the constant won't be created in the literal pool unless we call the intern() method.

In terms of optimization, we should use the String literal notation when possible. It is easier to read and it gives the compiler a chance to optimize our code.

In Java Is it efficient to use new String() instead of double quotes when string is really large and not using again?

1 Answers1