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When and where static blocks are executed in java?
A static block is a block of code with a static keyword. In general, these are used to initialize the static members. JVM executes static blocks before the main method at the time of class loading.
Example
public class MyClass {
static{
System.out.println("Hello this is a static block");
}
public static void main(String args[]){
System.out.println("This is main method");
}
}Output
Hello this is a static block This is main method
Executing a static block
JVM first looks for the main method (at least the latest versions) and then, starts executing the program including static block. Therefore, you cannot execute a static block without main method.
Example
public class Sample {
static {
System.out.println("Hello how are you");
}
}Since the above program doesn’t have a main method, if you compile and execute it you will get an error message.
C:\Sample>javac StaticBlockExample.java C:\Sample>java StaticBlockExample Error: Main method not found in class StaticBlockExample, please define the main method as: public static void main(String[] args) or a JavaFX application class must extend javafx.application.Application
If you want to execute static block you need to have Main method and, static blocks of the class get executed before main method.
Example
public class StaticBlockExample {
static {
System.out.println("This is static block");
}
public static void main(String args[]){
System.out.println("This is main method");
}
}Output
This is static block This is main method
Updated on: 30-Jul-2019
2K+ Views
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