Command line input


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  1. #1
    Basu Guest

    Command line input


    Hi,
    I would like to know how can i accept user input in the middle of the execution.
    I know using java prgnam paramete we can get user input but in middle of
    the program I need a way to get a value from the user.

    Please help me how to do this.

    Thanks
    Basu



  2. #2
    Tom Duffy Guest

    Re: Command line input


    Hello Basu:

    Here's an example that gathers input for a Quadratic equation and then solves
    it. It really only uses the readDouble() method of the Input class and I've
    included readInt() and readString().

    Hope this helps.

    Tom Duffy


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


    public class Quadratic {

    static public void main(String args[]) {
    System.out.println("This program computes the roots of quadratic
    equations of the form Ax^2 + Bx + C");
    //Read in coefficients
    System.out.print("Please enter a value for A > ");
    double a = Input.readDouble();
    System.out.print("Please enter a value for B > ");
    double b = Input.readDouble();
    System.out.print("Please enter a value for C > ");
    double c = Input.readDouble();
    //Calculate discriminant
    double discriminant = (Math.pow(b, 2))-(4*a*c);
    if(discriminant<0)
    System.out.println("Equation has no real roots.");
    else{
    //Find real roots
    double x1 = (-1*b+(Math.sqrt(discriminant)))/(2*a);
    double x2 = (-1*b-(Math.sqrt(discriminant)))/(2*a);
    //If x1=x2 the there is only one root
    if(x1==x2)
    System.out.println("The root of the equation is " + x1);
    else
    System.out.println("The roots of the equation are " +
    x1 + " and " + x2);
    }
    System.out.println();
    }

    }

    class Input{
    static private StringTokenizer stok;
    static private BufferedReader br
    = new BufferedReader(new InputStreamReader(System.in));

    public static int readInt()
    { int i = 0;
    try
    { String str = br.readLine();
    StringTokenizer stok = new StringTokenizer (str);
    i = new Integer (stok.nextToken ()).intValue ();
    }
    catch (IOException e)
    { System.out.println(e); }
    return i;
    }

    public static double readDouble()
    { double d = 0;
    try
    { String str = br.readLine();
    stok = new StringTokenizer (str);
    d = new Double (stok.nextToken ()).doubleValue ();
    }
    catch (IOException e) { System.out.println(e); }
    return d;
    }

    public static String readString()
    {
    String str = "";
    try
    { str = br.readLine();
    stok = new StringTokenizer (str);
    }
    catch (IOException e) { System.out.println(e); }
    return str;


    }
    }



    "Basu" <basusm@hotmail.com> wrote:
    >
    >Hi,
    >I would like to know how can i accept user input in the middle of the execution.
    >I know using java prgnam paramete we can get user input but in middle of
    >the program I need a way to get a value from the user.
    >
    >Please help me how to do this.
    >
    >Thanks
    >Basu
    >
    >



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