array help


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Thread: array help

  1. #1
    Join Date
    Jan 2004
    Posts
    1

    Question array help

    Hi and thanks in advanced.

    this is my first attempt at java and im having trouble because i want to do things like in C++.

    ok i simply would like to create a program that will ask the user to enter a number of grades to be averaged. Store that number in a variable. Insert the veriable number in an array ( to set size ). Then promt the user to enter the gpa's to be averaged and save them in the array. heres my code so far.
    Code:
    import javax.swing.*;
    import java.text.*;
    
    public class average
    {
    public static void main(String args[])
    {
    String input;
    int a = 0;
    int c = 1;
    double b = 0;
    
    
    input = JOptionPane.showInputDialog("Please enter the number of grades to enter");
    a = Integer.parseInt(input);
    
    double[] average;
    average = new double[a];
    
    while(c <= a)
    {
    average[b] = JOptionPane.showInputDialog("Enter gpa #" + c); // <---------ERROR HERE
    c =c+1;
    }
    //more to come here
    System.exit(0);
    }
    }
    i dont know enough java to know why this error is here, this is the error
    Code:
    C:\java>javac average.java
    average.java:22: possible loss of precision
    found   : double
    required: int
    average[b] = JOptionPane.showInputDialog("Enter gpa #" + c);
            ^
    average.java:22: incompatible types
    found   : java.lang.String
    required: double
    average[b] = JOptionPane.showInputDialog("Enter gpa #" + c);
                                            ^
    2 errors
    lol i hope any1 can help. again thanks in advanced and god bless

    g.g.

    [ArchAngel added CODE tags]

  2. #2
    Join Date
    Mar 2003
    Posts
    834
    None of your problems are really Java-specific - they're all typing problems that you get in any typed language.

    1. You're trying to index an array with a varible of type 'double' (the variable 'b'). This doesn't make sense - it's equivalent to typing myArray[10.3]! The compiler message is saying that it expects you to use an 'int', rather than 'double'.

    2. You're trying to assign a 'String' object (the value returned from .showInputDialog(...)) to a 'double' primitive (an element of the 'average' array). You can't just do that, you must parse the String into a double. For this, you can use Double.parseDouble(String):

    http://java.sun.com/j2se/1.3/docs/api/index.html

    Hope this helps.
    ArchAngel.
    O:-)

  3. #3
    Join Date
    Feb 2004
    Posts
    808
    hey wait a minute.. i know you..

    (time to add my signature

  4. #4
    Join Date
    Mar 2003
    Posts
    834
    hehe...
    ArchAngel.
    O:-)

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