How to pass String value from sub method to main method in java?

Question

public class NewTest {
    @Test
    public static void main(String [] args) throws IOException {
        new NewTest();
        NewTest.test();
        System.out.println(myname);
    }
    public static void test(){
        String myname = "Sivarajan";
    }
}

How to print myname ? Initialization error appeared while running this program.

Answer 1

Java variables have different scopes . If you define a variable inside a method it is non usable inside another method.

ways to fix it in your code:

1 Make the variable a member class

 public class NewTest {

    public static String myname = "Sivarajan";

    @Test
    public static void main(String [] args) throws IOException  
    {
        /*Note that since you are working with static methods 
         and variables you don't have to instantiate any class*/
        System.out.println(myname);
    }

2 Make test return a String

public class NewTest {

    @Test
    public static void main(String [] args) throws IOException  
    {
        NewTest newt = new NewTest();
        System.out.println(newt.test());
    }

    //Note that we did remove the static modifier
    public String test(){
        String myname = "Sivarajan";
        return myName;
        //or simply return "Sivarajan";
    }
}

Further reading:

http://docs.oracle.com/javase/tutorial/java/javaOO/variables.html

http://java.about.com/od/s/g/Scope.htm

Answer 2

Because your variable myname is declared and initialized inside of the test() method, it is unusable anywhere else in your program. You could have the test() method return a String like this:

public class NewTest {
    @Test
    public static void main(String [] args) throws IOException {
        new NewTest();
        NewTest.test();
        System.out.println(test());
    }
    public static String test() { //Changed to return a String
        return "Sivarajan";
    }
}

or declare it as a class variable and then use it in all methods of the class thereafter

public class NewTest {
    String myname = "Sivarajan"; //added myname as a class variable

    @Test
    public static void main(String [] args) throws IOException {
        new NewTest();
        NewTest.test();
        System.out.println(myname); 
    }
}

Answer 3

What I think you are trying to achieve involves using 'fields' of an object. What you have done is declared a variable inside a method, meaning it can only be referenced inside that method. By declaring a field you can then create objects of your class, and each one will have that field to access, like the below:

   public class NewTest {
      public static void main(String [] args) {
        //Create NewTest object
        NewTest  tester = new NewTest();

        //Run the method on our new Object
        tester.test();

        //Print the field which we just set
        System.out.println(tester.myName);
      }

      //Set the field
      public void test(){
        myName = "Sivarajan";
      }

     //A public field which is accessible in any NewTest object that you create
     public String myName = "";
  }