Why there is no null pointer exception?

Question

In the documentation code of java "out" is an object of PrintStream class which is initialized in the System class of package lang.This object "out" is initialized to null.So why does'nt the code throws a null pointer exception whenever the line

System.out.println(...); is used

http://stackoverflow.com/questions/3406703/whats-the-meaning-of-system-out-println-in-java — Suraj Rao, Apr 25 '17 at 09:16
because the `JVM` initializes `out` with `null`, and afterwards sets it to the default `PrintStream` provided — SomeJavaGuy, Apr 25 '17 at 09:17
[just going to throw this in, as i feel this should be the actual duplicate question](http://stackoverflow.com/questions/31743760/system-out-is-declared-as-static-final-and-initialized-with-null) — SomeJavaGuy, Apr 25 '17 at 09:23

score 3 · Answer 1 · answered Apr 25 '17 at 09:18

It is the field declaration.

Look at the initializeSystemClass() static method :

setOut0(newPrintStream(fdOut, props.getProperty("sun.stdout.encoding")))

The out is well initialized at a time by the VM.

The method is commented with this :

/**
 * Initialize the system class.  Called after thread initialization.
 */

score -1 · Answer 2 · answered Apr 25 '17 at 09:17

-1

The .out variable is a static variable of System. It's the default outputStream and not null.

Java Documentation: This stream is already open and ready to accept output data.

answered Apr 25 '17 at 09:17

Phillip K

7
3

This is wrong. It is first initialized to null, then later to the correct `PrintStream`. – marstran Apr 25 '17 at 09:18
`out` is actually a `final static` variable and will be initialized later on [see this](http://stackoverflow.com/questions/31743760/system-out-is-declared-as-static-final-and-initialized-with-null) – SomeJavaGuy Apr 25 '17 at 09:19
It is a final static variable that is initialised to null. – iavanish Apr 25 '17 at 09:19
Okay you are right. Sorry for the wrong information. – Phillip K May 10 '17 at 04:43

Why there is no null pointer exception?

2 Answers2