Underscores in literals are not supported at this language level

Question

I got this error when creating a final double using underscores to make the double more readable. It was declared in a run() method.

public void run() {        
    final double nanoSeconds = 1_000_000_000.0 / 60.0;    
}

I'm using IntelliJ IDEA 12.

Solution

In IntelliJ IDEA you have to change Project language level in project settings to 7.0 level:

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