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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