java - PrintStream object out is initialized by null, how we call method on it?

Question

I have seen in the System class that the out object (of type PrintStream) is initialized with a null value. How can we call method like System.out.prinln("");? In System class out variable initialized like this way:

package java.lang;

public final class System {
    public final static PrintStream out = nullPrintStream();

     private static PrintStream nullPrintStream() throws NullPointerException {
        if (currentTimeMillis() > 0) {
            return null;
        }
        throw new NullPointerException();
     }
}

As per shown above code out variable initialized by null and this variable is final, so it can not initialized further then how can we use "out" variable.

Answer 1

The explanation is in the comments:

/**
 * The following two methods exist because in, out, and err must be
 * initialized to null.  The compiler, however, cannot be permitted to
 * inline access to them, since they are later set to more sensible values
 * by initializeSystemClass().
 */

And initializeSystemClass() uses native methods to initialize the standard streams to non-null values. Native code can reinitialize variables that are declared final.