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Thread: learning the try and catch

  1. #1
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    Post learning the try and catch

    Hey everyone, I'm taking a java class and this is 3rd week. Right now we are learning about arrays and using the try/catch. What I need help with is with this code below, I am trying to just display information about buildings. The application is good but not with the try and catch statement. I'm trying to just display the message of "please enter a building number" when a user puts a letter instead of a number(InputMismatchException) and then the user would have to put in one of the numbers. But when it runs and i put in a letter, it reads the message, but it always outputs the first building information, any help? thanks

    package username;
    import java.util.InputMismatchException;
    import java.util.Scanner;
     
    //TallBuildings
    public class TallBuildings {
    //compare heights of buildings
    	public static void main(String[] args)
    	{		
    		//create local variables
    		int i = 0;
    		int b = 0;
    		Scanner scanIn = new Scanner(System.in);
     
    		//create building array
    		Building[] bldgs = new Building[5];
     
    		//create 5 buildings and save in array
    		bldgs[0] = new Building();
    		bldgs[0].name = "Sky Tower";
    		bldgs[0].location = "China";
    		bldgs[0].year = 2013;
    		bldgs[0].height = 2750;
     
    		bldgs[1] = new Building();
    		bldgs[1].name = "Sears Tower";
    		bldgs[1].location = "Chicago";
    		bldgs[1].year = 21974;
    		bldgs[1].height = 1451;
     
    		bldgs[2] = new Building();
    		bldgs[2].name = "One World Trade Center";
    		bldgs[2].location = "New York";
    		bldgs[2].year = 1972;
    		bldgs[2].height = 1368;
     
    		bldgs[3] = new Building();
    		bldgs[3].name = "Empire State Building";
    		bldgs[3].location = "New York";
    		bldgs[3].year = 1931;
    		bldgs[3].height = 1250;
     
    		bldgs[4] = new Building();
    		bldgs[4].name = "Chrysler Building";
    		bldgs[4].location = "New York";
    		bldgs[4].year = 1930;
    		bldgs[4].height = 1046;
     
    		//display the 5 buildings
    		while (i < 5) {
    			System.out.println((i+1) + "-" + bldgs[i].name);
    			i++;
    		}
     
    		//ask user which building they want
    		try {
    			System.out.println("\nWhat building information do you need?");
    			b = scanIn.nextInt();
    			b--;
    		} catch(InputMismatchException ime) {
    			System.out.println("Please enter in a building number");
    		}
     
    		//Display building information
    		System.out.println(bldgs[b].name);
    		System.out.println(bldgs[b].location);
    		System.out.println(bldgs[b].year);
    		System.out.println(bldgs[b].height);
    Last edited by Norm; January 23rd, 2014 at 06:23 AM. Reason: quote tags changed to code tags


  2. #2
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    Default Re: learning the try and catch

    This working nice try it out


    Code removed.

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    Default Re: learning the try and catch

    @jhansitenali: Please don't just post solutions or near-enough that could be used as solutions. Focus on the question and guide the OP to a solution, pushing lightly in the correct direction at first. Most are prohibited from using someone else's answer, and a solution with no explanation is often worthless for increasing the OP's understanding. For more info on why spoon feeding is discouraged here and on most forums that want to help people gain understanding, please read The Problem With Spoon-feeding.

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    Wink Re: learning the try and catch

    hi,

    I hope it will help you....

    try {
    System.out.println("\nWhat building information do you need?");
    b = scanIn.nextInt();  //Here itself you r getting exception so it wont go to the next line. The variable "b" having only initialized value "0". Thats why it is executing only "first building information
    b--;
    }

    You can do one thing put printing statments with in the "try" block. If you give correct number it wil print particular building information otherwise it wont print anything.

    Thanks,

  5. #5
    Super Moderator Norm's Avatar
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    Default Re: learning the try and catch

    What do you want the program to do when there is an exception?
    If you want it to go back and ask the user to input a valid value, you need to use a loop that exits when a valid value is entered and loops back when the input is invalid.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: learning the try and catch

    Sorry for the late response, I haven't been taught much about loops yet, I think we used only one before but she was just showing an example of a code in class of what we will be able to do after taking this class. What kind of loop command could I use?

    Also with ganeprog comment, thanks

  7. #7
    Super Moderator Norm's Avatar
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    Default Re: learning the try and catch

    You need to answer this question first:
    What do you want the program to do when there is an exception?
    then decide how to do it.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: learning the try and catch

    I want the program to allow the user to input one of the 5 building numbers again after the exception. The programs purpose is to ask the user wat building information they want and when they input the number corresponding with the building it will display that building info, but if the user inputs and invalid number or letter then it will display an error message allowing the user to input a correct number. I just don't understand how to do that if someone could explain the steps, thanks

  9. #9
    Super Moderator Norm's Avatar
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    Default Re: learning the try and catch

    allow the user to input one of the 5 building numbers again
    Doing something "again" is what loops are for. If your assignment requires the code to do things "again" then you need to use a loop.

    See the tutorial: The while and do-while Statements (The Java™ Tutorials > Learning the Java Language > Language Basics)
    If you don't understand my answer, don't ignore it, ask a question.

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