Core Java - Fundamentals V (Var-args, main and command-line arguments)

Var-arg Methods

• Introduced in 1.5 [eg: m1(int... x] , m1(10,20)]
• Internally it is implemented as single dimentional array concept.
• A method can take only 1 var-arg parameter and it should be at last incase of mixed parameters (eg : m1(int x, String... y).
• Also it gets least priority.
• Single dimensional array can be replaced by var-arg but reverse is not true.

Main Method

• JVM finds the main method or gives error if  not found (NoSuchMethodError : Main)
• Signature is fixed. Else we get (NoSuchMethodError : Main) 

         public static void main(String args[])

• public - > to be called from anywhere
• static -> without an existing object JVM should be able to call this method
• void -> main method cannot return anything to JVM
• main-> name of method configured in JVM (can be changed to anything else too)
• Commandline arguments
• It can be static public too, also String args[], String[] args,String []args, String... args is acceptable
• main can have final,synchronized and strictfp modifiers too.
• Inheritance concept is applicable, eg parent class main will be executed if child doesn't have main.
• Overriding is also applicable but it is method hiding.Overloading is also applicable but JVM calls only String args[].

Command-line Arguments

• Passing from command prompt.
• Space is default separator, if we need to include space then we have to enclose in double quotes.