what does static { // some code } mean?

Question

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Static Initialization Blocks

What does the following mean in java?

static {                                        
  WritableComparator.define(IntPair.class, new Comparator());
}

The problem is that those who ask this question are not aware of that this thing is called a "static initializer block" — Val, Jan 18 '13 at 19:19

score 9 · Answer 1 · answered Jan 18 '13 at 19:09

9

That means static initialization block which will be executed on class load.

If initialization requires some logic (for example, error handling or a for loop to fill a complex array), simple assignment is inadequate. Instance variables can be initialized in constructors, where error handling or other logic can be used. To provide the same capability for class variables, the Java programming language includes static initialization blocks.

answered Jan 18 '13 at 19:09

kosa

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read the link. it is explained there. – Femaref Jan 18 '13 at 19:10
Java tutorial page about static: http://docs.oracle.com/javase/tutorial/java/javaOO/initial.html – cjstehno Jan 18 '13 at 19:10
@MedicineMan: Add link to answer which explains more details and text which describes why we need it. – kosa Jan 18 '13 at 19:10

score 1 · Answer 2 · answered Jan 18 '13 at 19:11

It means that the code within that block will run once, when the type is loaded, before any constructors are called, but after any field initialisers are run.

Note that you cannot set any instance fields in the static block. There is no concept of this in there, just as in any other static methods.

what does static { // some code } mean?

2 Answers2