Run --> Run Configurations --> Arguments (it is the 2nd tab on the right) --> Program arguments

You can use java.util.Scanner (API):

import java.util.Scanner;

//...

Scanner in = new Scanner(System.in);
int num = in.nextInt();

It can also tokenize input with regular expression, etc. The API has examples and there are many others in this site (e.g. How do I keep a scanner from throwing exceptions when the wrong type is entered?).

Eclipse has a console, its typically located at the bottom of your java perspective. If its not there just go to Window->Show View->Console.

If I remember correctly, you can actually type in Eclipse's Java console and that will be sent through the standard input stream, System.in (probably depending on the application's run configuration).

However the standard way of doing this is to pass a number of strings on the command line, which will appear as the elements of the String[] parameter to your application's main method.

Alternatively you can get input in via flat files, from a database, through sockets etc. though this is, as you might expect, a lot more complex and should certainly not be considered for a "Hello World" type application. Java web services, for example, do take their input via network sockets rather than via the command line as this latter would restrict them somewhat. ;-)

In your parseProblem() method, you are trying to read from command line arguments.

To provide command line arguments do the following steps:

Right click on the class. Select Run As -> Run Configurations...

Double click on Java Application on the left side panel.

Go to (x)= Arguments tab on the right side panel.

Under Program Arguments field, provide your input for the program.

In your case, input argument should be something similar to:

030400000
870306001
004980000
906034000
005000300
000750204
000043700
500608032
000002080

As per the code you downloaded, "0" represents blank value.

To pass arguments to a Java program via Eclipse, you should use the Arguments tab in Run > Run Configurations. Example:

Arguments

Code

public static void main(String[] args) {
    System.out.println(args[0]);
    System.out.println(args[1]);
    System.out.println(args[2]);
}

Result

33
twitter
400.23

java.util.Scanner is the best choice for this task.

From the documentation:

For example, this code allows a user to read a number from System.in:

 Scanner sc = new Scanner(System.in);
 int i = sc.nextInt();

Two lines are all that you need to read an int. Do not underestimate how powerful Scanner is, though. For example, the following code will keep prompting for a number until one is given:

Scanner sc = new Scanner(System.in);
System.out.println("Please enter a number: ");
while (!sc.hasNextInt()) {
    System.out.println("A number, please?");
    sc.next(); // discard next token, which isn't a valid int
}
int num = sc.nextInt();
System.out.println("Thank you! I received " + num);

That's all you have to write, and thanks to hasNextInt() you won't have to worry about any Integer.parseInt and NumberFormatException at all.

See also

• Java Tutorials/Essential Classes/Basic I/O/Scanning and Formatting

Related questions

• How do I keep a scanner from throwing exceptions when the wrong type is entered? (java)
• How to use Scanner to accept only valid int as input

Other examples

A Scanner can use as its source, among other things, a java.io.File, or a plain String.

Here's an example of using Scanner to tokenize a String and parse into numbers all at once:

Scanner sc = new Scanner("1,2,3,4").useDelimiter(",");
int sum = 0;
while (sc.hasNextInt()) {
    sum += sc.nextInt();
}
System.out.println("Sum is " + sum); // prints "Sum is 10"

Here's a slightly more advanced use, using regular expressions:

Scanner sc = new Scanner("OhMyGoodnessHowAreYou?").useDelimiter("(?=[A-Z])");
while (sc.hasNext()) {
    System.out.println(sc.next());
} // prints "Oh", "My", "Goodness", "How", "Are", "You?"

As you can see, Scanner is quite powerful! You should prefer it to StringTokenizer, which is now a legacy class.

See also

• Java Tutorials/Essential Classes/Regular expressions
• regular-expressions.info/Tutorial

Related questions

• Scanner vs. StringTokenizer vs. String.Split

One of the simplest ways is to use a Scanner object as follows:

import java.util.Scanner;

Scanner reader = new Scanner(System.in); // Reading from System.in
System.out.println("Enter a number: ");
int n = reader.nextInt(); // Scans the next token of the input as an int
// Once finished
reader.close();

Are you trying to create a Java project, take two numbers as output, and print the sum? If that is true, you should really read over some basic Java/Eclipse tutorials. I would suggest the Eclipse and Java Tutorial for Total Beginners -- it should get you started on how to create/open a project and how to use eclipse.

As for getting two numbers and printing out the sum, you should really learn Java IO and do this yourself, but a quick google search gets exactly what you want:

import java.io.*; //imports java.io class 

/* 
 * Adds 2 integers given by the user, then prints out the sum. 
 * Directly copied from http://www.dreamincode.net/code/snippet492.htm, as I 
 * am too lazy to write this myself :)
 */ 

public class Add2number { 

  //main(): application entry point 
  public static void main(String[] args) throws IOException { 

        //set input stream 
        BufferedReader stdin = new BufferedReader( 
              new InputStreamReader(System.in)); 

        //get numbers from user input 
        //asks user for 1st number, then converts it to an integer 
        System.out.print("Enter first integer: "); 
        int x = Integer.parseInt(stdin.readLine()); 
        //asks user for 2nd number, than converts it to an integer 
        System.out.print("Enter second integer: "); 
        int y = Integer.parseInt(stdin.readLine()); 

        //add x,y 
        int sum = x + y; 

        //Display sum of x,y 
        System.out.println("The sum is: " + sum); 
  }//ends main 

}//ends addReadLine

You have to return a value in all branches, there are 3 possibilities:

1) Return an int in the else branch:

public int rNum(String nums, String lets){

    int z;

    if(nums == "yes" && lets == "yes"){
        z = (int)Math.random()*36;
        return z;

    } else if(nums == "yes"){
        z = (int)Math.random()*10;
        return z;   

    } else if(lets == "yes"){
        z = (int)Math.random()*26 + 10;
        return z;

    } else {
        System.out.println("Sorry, you need either letters or numbers in your password.");
            return -1;
    }
}

2) Throw an unchecked exception

public int rNum(String nums, String lets){

    int z;

    if(nums == "yes" && lets == "yes"){
        z = (int)Math.random()*36;
        return z;

    } else if(nums == "yes"){
        z = (int)Math.random()*10;
        return z;   

    } else if(lets == "yes"){
        z = (int)Math.random()*26 + 10;
        return z;

    } else {
        System.out.println("Sorry, you need either letters or numbers in your password.");
        throw new RuntimeException("Sorry, you need either letters or numbers in your password.");
    }
}

3) Throw a checked exception

public int rNum(String nums, String lets) throws Exception {

    int z;

    if(nums == "yes" && lets == "yes"){
        z = (int)Math.random()*36;
        return z;

    } else if(nums == "yes"){
        z = (int)Math.random()*10;
        return z;   

    } else if(lets == "yes"){
        z = (int)Math.random()*26 + 10;
        return z;

    } else {
        System.out.println("Sorry, you need either letters or numbers in your password.");
        throw new Exception("Sorry, you need either letters or numbers in your password.");
    }
}

The identifier int is a reserved keyword in Java and cannot be used as a variable name.

I would suggest not abbreviating your attributes, but instead use full words:

int strength;
int agility;
int intelligence;

Even if there were a way to create a variable named int, the resulting code would be confusing to read later.