Baffled while calling method

Code:

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import java.io.*;
import java.util.Scanner;

class project12 {
    public void mast(String[] args) { //METHOD DECLARED HERE
        int num1 = 10429;
        int num2 = 15;
        double dnum1 = 47.8;
        double dnum2 = 5;
        System.out.println("Hello World!");
        System.out.println(num1 + "x" + num2 + "=" + (num1+num2) + " Hooray for addition");
        System.out.println(dnum1 + " devided by " + dnum2 + " gives us " + (dnum1/dnum2) + ", But you couldn't do this with integers so i used doubles\n");

        //counting system: example of the for loop which can do all that a while loop can do
        int i;
        System.out.println("below is an example of for loops, it repeats a proccess while counting to 10:");
        for (i=1; i<=10; i++) {
            System.out.println("count:" + i);
        }

        //Use of condition statements to generate boolean variable output
        System.out.println("\nif the following statements are true then it should show:");
        System.out.println(num1 + " > " + num2 + " is " + (num1>num2));
        System.out.println(num1 + " < " + num2 + " is " + (num1<num2));

        //input and conditions (requires 'import java.io.*;' for reader.readLine()):
        System.out.println("would you like to use the manuel counter? (y/n): ");
        int cuse = 'y'; //counter-use? ~= cuse
        try {
            cuse = System.in.read();
        }catch(java.io.IOException exp){ exp.printStackTrace();}

        if (cuse=='y') {
            int cnum = 10;
            System.out.println("enter a number (prefferably within the known and feasible universe): ");
            Scanner scan = new Scanner(System.in); //required for scan.nextInt()
            cnum = scan.nextInt(); //scans for integer input
            int dd;
            System.out.println("counting to " + cnum + ":");
            for (dd=1; dd<=cnum; dd++) {
                System.out.println(dd);
            }
        }
        else {
            System.out.println("??? wtf??? why... what... wtf???");
        }
    }
    public static void main(String[] args) {
        int repet = 1;
        while (repet==1) {
            mast(); //METHOD CALLED HERE
            int re = 'y';
            System.out.println("\n\nwould you like to stay? (y/n): ");
            try {
                re = System.in.read();
            }catch(java.io.IOException exp){ exp.printStackTrace();}
            if (re=='y') {
                continue;
            } else {
                repet = 3;
                break;
            }
        }
        System.out.println("bye for now\n");
    }
}

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i am very new to java and so im basically picking things up and testing them as i go along, this program IS completely useless, and (from my knowledge of other languages) chaotic and badly laid out. i have tried to integrate a lot of different concepts to practice my java, and it all worked untill i tried to make the method that had previously been main (mast() where is says METHOD DECLARED HERE) a separate method and make a new main method which i call the mast() method from. I compiled it with javac in ubuntu and this is what i got:

Code:

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james@james-laptop:~/Desktop/coding/Jcoding$ javac pro1-3.java
pro1-3.java:54: main(java.lang.String[]) in project13 cannot be applied to ()
            main();
            ^
1 error

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i figure it is something gone wrong with my call of the mast function - err.. i mean method - but i don't know the precise nature of the problem. Could somebody please explain where i have gone wrong and how to put it right?

(or direct me to a previous post that i haven't found)

thanks in advance

Quote:

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Originally Posted by javajames

Code:

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class project12 {
    public void mast(String[] args) { } //METHOD DECLARED HERE
    public static void main(String[] args) {
            mast(); //METHOD CALLED HERE
    }
}

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I removed (quite) a bit of your code: you mast( ... ) method wants a String[] argument as its parameter but you're calling it without any parameter(s) at all; your compiler doesn't like that (it was complaining about the mast( ... ) method, not the main( ... ) method).

kind regards,

Jos

You are also attempting to call a non-static method from a static context

Code:

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class classname {
    public static void mast(String[] args) {
        code_goes_here();
    }
    public static void main(String[] args) {
        mast(java.lang.String[]);
    }

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Is this correct?
What should my arguments be? i am currently in school so don't have a compiler with me but the java.lang... is just a geuss, could i put mast(void)? I just need to define a void function (method) as in c++. Could someone give me some example code for defining and calling void methods.

Quote:

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Originally Posted by javajames

Code:

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class classname {
    public static void mast(String[] args) {
        code_goes_here();
    }
    public static void main(String[] args) {
        mast(java.lang.String[]);
    }

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Is this correct?
What should my arguments be? i am currently in school so don't have a compiler with me but the java.lang... is just a geuss, could i put mast(void)? I just need to define a void function (method) as in c++. Could someone give me some example code for defining and calling void methods.

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Nope, Java.lang.String[] can't be an actual parameter, you have to pass it an array of Strings (as is done with the main( ... ) method; i.e. args is an array of Strings. You could pass it to your mast method: mast(args); you wrote that method yourself so you should know what that mast( ... ) method wants to do with its parameter and what it expects ...

edit: I noticed that your mast method doesn't use its parameter at all; define it as follows:

Code:

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public static void mast() { ... }

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kind regards,

Jos

will try this, get back to you if it is successful thanks for your help

If mast is defined without a parameter, then am i able to call it without parameter i.e:

Code:

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public static void mast() { [I]code[/I] }
[I]in main:[/I]
    mast();

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i will admit that i wrote that method blindly, i simply used the same format as main, but now that i know how to create a void method i understand this a lot more - so i didn't know what mast(...) wanted to do with the parameters. I have learnt a lot here thank you

could i do without the 'static' part

What I generally do is to use a constructor, and having main() only create a new instance of the class. So for instance:

Code:

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  public static void main(String[] args)
  {
    new ClassConstructor(args);
  }
  public ClassConstructor(String[] args)
  {
    // Do stuff here
  }

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This means that yuo don't have to use static methods or variables anywhere in your class, unless you really need it.

Quote:

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Originally Posted by javajames

could i do without the 'static' part

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You can think of 'static' methods and fields as globals in c++, if they are declared public you can access them from anywhere in your application.
All methods and fields that does not have the 'static' part are called 'instance' methods and fields. These methods and fields can not be accessed without creating an object of the class first.

This might give you a better understanding about static and non-static:

Code:

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public class TestClass {
   
    public static void main(String[] args) {
        /*
        * The following call is valid. Remember, static methods can be called
        * from anywhere, including other static methods!
        */
        someStaticMethod();
       
        /*
        * The following call is not valid though, since this method is an
        * instance method (it's missing the 'static' keyword).
        * Uncomment the line below (remove the //) to see what I mean.
        */
       
        //someInstanceMethod();
       
        /*
        * So how do we access these methods? The only way to access them is by
        * creating an object first. Since 'someInstanceMethod()' is part of the
        * 'TestClass' class, we have to create an object of that class to access
        * the method. We will begin by declaring a new, local field.
        */
       
        TestClass someObject;
       
        /*
        * So have we created a new object now? Nope, not yet. All we have done
        * so far is declared a new field that will point to a 'TestClass' object.
        * Here is how you create a new object and assign it to the someObject
        * field.
        */
       
        someObject = new TestClass();
       
        /*
        * Finally we can access the instance method.
        */
       
        someObject.someInstanceMethod();
    }
   
    public static void someStaticMethod() {
        //Print some random garbage to the console.
        System.out.println("Hey there!");
    }
   
    public void someInstanceMethod() {
        //Print some random garbage to the console.
        System.out.println("Oh hi!");
    }
}

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thank you all