Can there exist two main methods in a Java program

Question

Can there exist two main methods in a Java program   Only by the difference in their arguments like   public static void main String   args    and second can be  public static void main StringSecond   args    If it is possible  which Method will be used as the entry point  How to identify this

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Case  1  gt  We have two main method but with  quot Main quot  AND  quot main2 quot  so jvm only a calling  quot main quot  method   2 gt  Same method but diff params  still jvm calling  quot main String   args   quot  meyhod  3 gt  Exactly same method but it gives copile time error as you can not have two same name method in a single class     Hope it will give you clear pic

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Yes it is possible to have two main   in the same program  For instance  if I have a class Demo1 as below  Compiling this file will generate Demo1 class file  And once you run this it will run the main   having array of String arguments by default  It won t even sniff at the main   with int argument    class Demo1      static int a  b      public static void main int args         System out println  Using Demo1 class Main with int arg         a  30       b  40       System out println  Product is    a b      public static void main String   args          System out println  Using Demo1 class Main with string arg          a  10        b  20        System out println  Product is    a b                 Output  Using Demo1 class Main with string arg Product is  200   But if I add another class named Anonym and save the file as Anonym java  Inside this I call the Demo1 class main   either int argument or string argument one   After compiling this Anonym class file gets generated     class Demo1          static int a  b      public static void main int args        System out println  Using Demo1 class Main with int arg        a  30      b  40      System out println  Product is    a b     public static void main String   args        System out println  Using Demo1 class Main with string arg         a  10       b  20       System out println  Product is    a b                        class Anonym  public static void main String arg           Demo1 main 1       Demo1 main null         Output  Using Demo1 class Main with int arg Product is  1200 Using Demo1 class Main with string arg Product is  200

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The answer is no  there can only one  main  method - where  main  means an entry point you can  run    You can code overloaded versions as in your example  but they can t be  run

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In Java  you can have just one public static void main String   args  per class  Which mean  if your program has multiple classes  each class can have public static void main String   args   See JLS for details

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Here you can see that there are 2 public static void main  String args    in a single file with the name Test java  specifically didn t use the name of file as either of the 2 classes names  and the 2 classes are with the default access specifier   class Sum        int add int a  int b            return  a b                 public static void main  String args              System out println   using Sum class            Sum a   new Sum            System out println  Sum is      a add 5  10               public static void main  int i            System out println   Using Sum class main function with integer argument            Sum a   new Sum            System out println  Sum is      a add 20  10             class DefClass        public static void main  String args              System out println   using DefClass            Sum a   new Sum            System out println  Sum is      a add 5  10            Sum main null           Sum main 1             When we compile the code Test java it will generate 2  class files  viz Sum class and DefClass class  and if we run Test java we cannot run it as it won t find any main class with the name Test  Instead if we do java Sum or java DefClass both will give different outputs using different main    To use the main method of Sum class we can use the class name Sum main null  or Sum main 1   Passing integer value in the DefClass main     In a class scope we can have only one public static void main  String args    per class since a static method of a class belongs to a class and not to its objects and is called using its class name  Even if we create multiple objects and call the same static methods using them then the instance of the static method to which these call will refer will be the same   We can also do the overloading of the main method by passing different set of arguments in the main  The Similar example is provided in the above code but by default the control flow will start with the public static void main  String args    of the class file which we have invoked using java classname  To invoke the main method with other set of arguments we have to explicitly call it from other classes

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That would be compilable code  as long as StringSecond was a class   However  if by  main method  you mean a second entry point into the program  then the answer to your question is still no   Only the first option  public static void main String   args   can be the entry point into your program   Note  however  that if you were to place a second main String    method in a different class  but in the same project  you could have multiple possible entry points into the project which you could then choose from   But this cannot conflict with the principles of overriding or overloading   Also note that one source of confusion in this area  especially for introductory programmers  is that public static void main String   args  and public static void main String     args  are both used as entry points and are treated as having the same method signature

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The signature of main method must be  public static void main String   args      The parameter s name can be any valid name The positions of static and public keywords can be interchanged The String array can use also the varargs syntax    A class can define multiple methods with the name main  The signature of these methods does not match the signature of the main method  These other methods with different signatures are not considered the  main  method

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There can be more than one main method in a single program  But JVM will always calls String   argument main   method  Other method s will act as a Overloaded method  These overloaded method s we have to call explicitly

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As long as method parameters  number  or  type  are different  yes they can  It is called overloading      Overloaded methods are differentiated by the number and the type of the arguments passed into the method   public static void main String   args    only main method with single String    or  String    as param will be considered as entry point for the program

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i have check in java version 1 6 0 32 multiple main method is working but there should one main method like public static void main String   args  of type signature  Ex is here which i had tested   public class mainoverload   public static void main String a        System out println   nIts   a     public static void main String args          System out println   nIts public static void main n        mainoverload main  Ankit        mainoverload main 15 23       mainoverload main 15     public static void main int a        System out println   nIts   a     public static void main int a int b        System out println   nIts   a     b

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the possibility of two main String   args  methods within the same scope create confusion for the JVM  It fails to  use them as overloaded methods  So the signatures in terms of parameters  must be different

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There can be more than one main method in a single program  Others are Overloaded method  This overloaded method works fine under a single main method  public class MainMultiple      public static void main String args            main 122          main  f           main  hello java             public static void main int i          System out println  Overloaded main    i            public static void main char i          System out println  Overloaded main    i            public static void main String str          System out println  Overloaded main    str

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Yes  Any class in Java can have multiple main methods  It s called Overloading  Overloaded methods are methods with same name but with different signatures  but there should only be one main method with parameters like this  -   String   args  or  String args     For example  -public class E    public static void main String args       System out println  Print A      public static void main String    args       System out println  Print B      public static void main int garbage       System out println  Print C      public static void main int i       System out println  Print D          The output of the above program will be  Print B  as only that main method contains the correct method signature identified by the Javac compiler and it compiles that only and leaves the rest

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The  below code in file  Locomotive java  will compile and run successfully  with the execution results showing   2 lt SPACE gt    As mentioned in above post  the overload rules still work for the main method  However  the entry point is the famous psvm  public static void main String   args    public class Locomotive       Locomotive     main  hi          public static void main String   args            System out print  2                public static void main String args            System out print  3     args

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The answer is Yes  but you should consider the following 3 points    No two main method parameter should be the same  Eg     public static void main int i    public static void main int i  int j  public static void main double j  public static void main String   args   Java   s actual main method is the one with  String   args   So the Actual execution starts from public static void main String   args   so the main method with  String   args  is must in a class unless if it is not a child class  In order for other main methods to execute you need to call them from inside the  String   args  main method    Here is a detailed video about the same  https   www youtube com watch v Qlhslsluhg4 amp feature youtu be

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Only public static void main String   args  counts   This is the only signature considered to be the true main    as the program entry point  I mean

[java] Can there exist two main methods in a Java program?

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