Static Blocks

Definition:

• A static block is a piece of code that is executed when the class is first loaded by the JVM.
• It is used to initialize static variables or perform tasks that need to be completed before the class can be used.

Purpose:

• Can be used to perform important initializations, such as establishing connections or calculating initial values.
• Useful for preparing the class before any instances are created or before static methods are called.

Execution:

• The static block is executed only once, as soon as the class is loaded, before any other code related to the class.
• It is executed even if no object of the class is created.

Code Example with Static Block:

StaticBlock.java

// Usa um bloco estático class StaticBlock { static double rootOf2; static double rootOf3; // Bloco estático para inicialização static { System.out.println("Inside static block."); rootOf2 = Math.sqrt(2.0); rootOf3 = Math.sqrt(3.0); } StaticBlock(String msg) { System.out.println(msg); } } class SDemo3 { public static void main(String args[]) { StaticBlock ob = new StaticBlock("Inside Constructor"); System.out.println("Square root of 2 is " + StaticBlock.rootOf2); System.out.println("Square root of 3 is " + StaticBlock.rootOf3); } }

• The message "Inside static block." shows that the static block was executed before the StaticBlock object was created.
• The values of rootOf2 and rootOf3 are calculated in the static block and are available before executing any method or object construction.

Advantage of Static Blocks:
They ensure that certain initializations are done safely and at the appropriate time, before the class is used.

Common Usage:

• Initiate complex static variables or perform initial configuration of resources that the class needs.

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