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Using Static Blocks in Java: Configuration Class Example

Java Static Members: Exercise-5 with Solution

Static Block for Initialization
Write a Java program to create a class called Configuration with a static block that initializes a static variable 'configValue' from a configuration file (simulated with a default value). Print the value of 'configValue' in the main method.

Sample Solution:

Java Code:

Configuration.java

// Define the Configuration class
public class Configuration {
    // Declare a static variable configValue
    public static String configValue;

    // Static block to initialize configValue
    static {
        // Simulating reading from a configuration file by assigning a default value
        configValue = "Default Config Value";
        System.out.println("Static block executed: configValue initialized");
    }

    // Main method to print the value of configValue
    public static void main(String[] args) {
        // Print the value of configValue
        System.out.println("Config Value: " + configValue);
    }
}

Output:

Static block executed: configValue initialized
Config Value: Default Config Value

Explanation:

  • Define the Configuration class:
    • The Configuration class is defined using the class keyword.
  • Declare a static variable configValue:
    • The static variable configValue is declared. It will hold the configuration value.
  • Static block to initialize configValue:
    • A static block is used to initialize the static variable configValue.
    • This block simulates reading from a configuration file by assigning a default value to configValue.
    • A message is printed to indicate that the static block has been executed and configValue has been initialized.
  • Main method to print the value of configValue:
    • The main method is defined to test the Configuration class.
    • It prints the value of configValue to the console.

Note on Java Static Members:

In the above exercise, the static members work by:

  • Static Variable: The static variable configValue is associated with the class Configuration, not with any instance. It can be accessed and modified by static methods and blocks.
  • Static Block: The static block is a special block of code that is executed when the class is first loaded into memory. It is used here to initialize the static variable configValue with a default value, simulating reading from a configuration file.
  • Main Method: The main method prints the value of configValue, demonstrating that the static block has successfully initialized it.

Java Code Editor:

Improve this sample solution and post your code through Disqus.

Java Static Members Previous: Using Static Final Variables in Java: Constants Class Example.
Java Static Members Next: Using Static Methods and Variables in Java: IDGenerator Example.

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