Exploring Main Method

Key Points

• main() method is a special method which will be called by the JVM.
• Standard signature of main():

    public static void main(String[] args) { }

static public void main(String[] args) { }

✔ Order of public and static can be changed.

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🔹 Important Notes

• You can overload the main() method 👉 But JVM always calls only:

public static void main(String[] args)

• main() acts as: 👉 Application launcher / entry point

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📘 Explanation of main() Components

Keyword	Meaning
public	Accessible from anywhere
static	Can be accessed without object (using class name)
void	Does not return any value to JVM
main	Method name (entry point)
String[]	Used to pass command-line arguments

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Lab410.java

class Lab410 {

  static {
    System.out.println("I am S.B");
  }

  public static void main(String[] args) {
    //  INVALID
    System.out.println("I am main()");
  }
}

Output:

• Runtime Error → No proper main method

---

Lab411.java

class Lab411 {

  static {
    System.out.println("I am S.B");
  }

  public static void main(String[] args) {
    System.out.println("I am main()");
  }
}

Output:

I am S.B
I am main()

---

Lab412.java

class Lab412 {

  public static final synchronizedstrictfpvoidmain(String... args) {
    System.out.println("I am main()");
  }
}

Notes:

• Multiple modifiers allowed
• String... args (var-args) is valid alternative

---

Lab413.java

class Lab413 {

  public static void main(String[] args) {
    System.out.println("main(String)");
  }

  public static void main(String[] args) {
    System.out.println("main(String[])");
  }

  public void main(int[] args) {
    System.out.println("main(int[])");
  }
}

Output:

main(String[])

Key Concept:

• JVM calls only:

public static void main(String[] args)

• Other overloaded methods are ignored unless called manually

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🧠 Summary

• ✔ main() = Entry point of Java program
• ✔ Must be public static void
• ✔ Parameter must be String[] (or String...)
• ✔ Overloading allowed but JVM ignores them

Lab414.java

class Lab414 {

  public static void main(String[] args) {
    System.out.println("main(String)");
  }

  public void main(int[] args) {
    System.out.println("main(int[])");
  }
}

---

Lab415.java

class Lab415 {

  {
    System.out.println("Lab415-I.B");
  }

  Lab415() {
    System.out.println("Lab415-D.C");
  }

  public static void main(String[] args) {
    System.out.println("main(String[])");
  }
}

---

Lab416.java

class Hello {

  public static void main(String[] args) {
    System.out.println("Hello - main");
  }
}

class Hai {

  public static void main(String[] args) {
    System.out.println("Hai - main");
    Hello.main(args);
  }
}