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Thread: How do I call a method from the main method?

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    Default How do I call a method from the main method?

    How do I invoke a method from the main method? does that make sense?


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    Default Re: How do I call a method from the main method?

    You us the method name and argument pattern to refer to it, e.g:

    public static void main(String[] args){
     
      //Will work
      someMethod("Hello World");
     
     
      //Wont work
      someMethod();
    }
     
    private void someMethod(String message){
      System.out.println("In someMethod, message = " + message);
    }


    Have a look at this and the next few tutorial pages:
    Defining Methods (The Java™ Tutorials > Learning the Java Language > Classes and Objects)

    You may also want to look in the tutorial section of this forum, people have written up some very good tutorials which should help.

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    Default Re: How do I call a method from the main method?

    public class className{

    public void method1(int n) {

    //code
    }
    public static void main (String args[]) {
    //how do I call method1?
    }

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    Default Re: How do I call a method from the main method?

    You use the method name, followed by parenthesis "()". You put arguments in the brackets, separated by a comma.

    A method is made up of several parts, lets look at:

    public void aMethod(String message)
    {
      //do stuff
    }


    First off, public: This is the modifier, namely the access modifier. This determines who has access to the method. To begin with, just make everything public so you don't run into any trouble. Other modifiers are things such as static, final, abstract, etc. but don't worry about them for now.
    Modifiers: Retrieving and Parsing Method Modifiers (The Java™ Tutorials > The Reflection API > Members)

    void: This is the return type, each method can only return one variable of a specific data type. void means the method dos not return anything. in place of void, you could put int, String, double, or any other data type (including your own custom classes). If you use anything other than void, your method must have a return statement

    public String aMethod()
    {
      return "Hello World";
    }

    For returning a value from a method, see: Returning a Value from a Method (The Java™ Tutorials > Learning the Java Language > Classes and Objects)


    aMethod(): This is the method name and what you use to refer to the method. If the method receives arguments, you need to put them in the parenthesis with the data type then variable name. If the method receives multiple args, you use a comma to separate them. You must pass args to a method in the same order which it receives them, e.g

    public void myMethod(String message, int number){}
     
    public static void main(String[] args){
      // calling myMethod with a String then an int will work
      myMethod("Hello", 5");
     
    // calling myMethod with an int, then a string wont
      myMethod(5, "Hello")
    }

    Passing values to methods: Passing Information to a Method or a Constructor (The Java™ Tutorials > Learning the Java Language > Classes and Objects)



    {
    //some code
    }
    :

    Your code goes in between the curly braces


    put it together:

     
    public static void main(String[] args){
      someMethod("Hello World");
      anotherMethod(1, "someText");
      String myText = aThirdMethod();
    }
     
    public void someMethod(String message){
      System.out.println("In someMethod, message = " + message);
    }
     
    public void anotherMethod(int quantity, String message){
      System.out.println("In anotherMethod, message = " + message + "  quantity = " + quantity);
    }
     
    public String aThirdMethod(){
       System.out.println("In aThirdMethod");
      return "Some meaningful text";
    }

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    Default Re: How do I call a method from the main method?

    Have a go at using the examples to call method1, let me know how you go

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    Default Re: How do I call a method from the main method?

    You didn't declare method1 as being static. If a method is not static, you must have an instance of that object to call that method. If it is static, you don't.

    See: Understanding Instance and Class Members (The Java™ Tutorials > Learning the Java Language > Classes and Objects)

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