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Thread: I/O List.java

  1. #1
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    Exclamation I/O List.java

    Write a program that allows the user to enter a list of up to 100 integers. Please check for boundary conditions, for example, the user has to enter more than 0 integers but not more then 100. The end of the list is indicated by the special value -1. The program then reads more integers (max. 100), and, for every value, tells whether or not the value appears in the first list. The program ends when the user enters -1 (for the second time). For example, for the input

    25 50 75 100 -1
    99 25 30 -1

    the program should respond:

    99: not in list
    25: yes, in list
    30: not in list

    So far I have the following

    public class List
    {
    public static void main(String[]args)
    {
    // Input of the FirstList by the user.
    int[] Firstlist = new int[100];
    int i = 0;
    int tempNum = StdIn.readInt();

    while (tempNum != -1)
    {
    Firstlist[i] = tempNum;
    tempNum = StdIn.readInt();
    i = i + 1;
    }
    System.out.println(Firstlist[2]);

    // Comparison
    int [] Secondlist = new int[100];
    int j = 0;
    int tempNum2 = StdIn.readInt();

    while (tempNum2 != -1)
    {
    Secondlist[j] = tempNum2;
    tempNum2 = StdIn.readInt();
    j = j + 1;
    }
    System.out.println(Secondlist[2]);

    }
    }

    How do I compare the second list with the first list...Also note that Im using StdIn.readInt(); and I have all the files to use it...I got them from "introduction to programming an indeseplinary approach" website.

  2. #2
    Super Moderator Norm's Avatar
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    Default Re: I/O List.java

    How do I compare the second list with the first list..
    How do you want to compare the arrays?
    If element by element, use a loop with an if test to compare the elements from each array.
    Otherwise explain what you mean by comparing the arrays.

  3. #3
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    Default Re: I/O List.java

    [QUOTE=Norm;60425]How do you want to compare the arrays?


    The program has to tell you whether or not a value in the second list appears in the first list.

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: I/O List.java

    That sounds like a search. Take an element from the second list and search the first list.

    When posting code, please wrap your code with[code=java]<YOUR CODE HERE>[/code] to get highlighting

  5. #5
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    Default Re: I/O List.java

    Instead of using arrays, try using a LinkedList:
    LinkedList<Integer> numbers1 = new LinkedList<Integer>();
    LinkedList<Integer> numbers2 = new LinkedList<Integer>();
     
    while(true){
    System.out.println("Enter number");
    int number = new Scanner(System.in).nextInt();
    if(number == -1){
    if(numbers1.size() > 0){
    break;
    }else{
    System.out.println("Need atleast one element inside list");
    }
    }else{
    if(numbers1.size() <= 100){
    numbers1.add(number);
    }else{
    System.out.println("Can't have more then 100 elements, ending list");
    break;
    }
    }
    }
     
    while(true){
    System.out.println("Enter number");
    int number = new Scanner(System.in).nextInt();
    if(number == -1){
    if(numbers2.size() > 0){
    break;
    }else{
    System.out.println("Need atleast one element inside list");
    }
    }else{
    if(numbers2.size() <= 100){
    numbers2.add(number);
    }else{
    System.out.println("Can't have more then 100 elements, ending list");
    break;
    }
    }
    }
     
    for(int i = 0; i < numbers2.size(); i++){
    System.out.println(String.format("%d: %s", numbers2.get(i), numbers1.contains(numbers2.get(i)) ? "is in list" : "not in list"));
    }

    I might be a little off with the brackets because I wrote that inside here instead of Eclipse, but yeah, you get the point.

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