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Thread: Problem to learn exceptions.

  1. #1
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    Default Problem to learn exceptions.

    Hi all.

    Im trying to learn how to make a own exceptions. I guess it's up to the structure im using etc. I have dropped from 11 errors down to 4. But now i would be pleased to get some help to get this done

     
    import java.util.Scanner; 
    import java.util.*; 
     
    public class omaPoikkeus { 
    	public static void main(String[] args) { 
    		Scanner lukija = new Scanner(System.in); 
    		int testattavaLuku = 0; 
    		boolean syöteOk = true; 
     
    		do { 
    			try { 
    				System.out.print("Anna testattava luku: "); 
    				testattavaLuku = lukija.nextInt(); 
    				syöteOk = true; 
    			} catch (InputMismatchException e) { 
    				System.out.println("Et antanut kokonaislukua!"); 
    				syöteOk = false; 
    				lukija.nextLine(); 
    			} 
    		} while(!syöteOk); 
     
    		try { 
    			testaaArvo(testattavaLuku); 
    			System.out.println("Arvo oli välillä 5-10."); 
    		} catch(PieniPoikkeus e) { 
    			System.out.println("PieniPoikkeus siepattu!"); 
    			tulostaVirheTeksti(e); 
    		} catch(SuuriPoikkeus e) { 
    			System.out.println("SuuriPoikkeus siepattu!"); 
    			tulostaVirheTeksti(e); 
    		}           
    	} 
     
    	// Sinun koodi tulee tähän
    	public static int testaaArvo(int luku) throws PieniPoikkeus, SuuriPoikkeus{
    		if (luku < 5) {
    			throw new PieniPoikkeus("Luku on alle 5.");
    		}
     
    		if (luku > 10) {
    			throw new SuuriPoikkeus("Luku on yli 10.");
    		}
     
    		return luku;
    	}
     
    	public static void tulostaVirheTeksti(String viesti) {
    		System.out.println(viesti);
    	}
     
     
    	// Poikkeukset
    	class PieniPoikkeus extends Exception{
     
    		// Konstruktori
    		public PieniPoikkeus(String exc) {
    			super(exc);
    		}
     
    		public String getMessage() {
    			return super.getMessage();
    		}
    	}
     
    	class SuuriPoikkeus extends Exception{
     
    		// Konstruktori
    		public SuuriPoikkeus(String exc) {
    			super(exc);
    		}
     
    		public String getMessage() {
    			return super.getMessage();
    		}
    	}
    }

    What is the tree where im bangin my head currently?

    omaPoikkeus.java:28: error: method tulostaVirheTeksti in class omaPoikkeus cannot be applied to given types;
    tulostaVirheTeksti(e);
    ^
    required: String
    found: omaPoikkeus.PieniPoikkeus
    reason: actual argument omaPoikkeus.PieniPoikkeus cannot be converted to String by method invocation conversion
    omaPoikkeus.java:31: error: method tulostaVirheTeksti in class omaPoikkeus cannot be applied to given types;
    tulostaVirheTeksti(e);
    ^
    required: String
    found: omaPoikkeus.SuuriPoikkeus
    reason: actual argument omaPoikkeus.SuuriPoikkeus cannot be converted to String by method invocation conversion
    omaPoikkeus.java:38: error: non-static variable this cannot be referenced from a static context
    throw new PieniPoikkeus("Luku on alle 5.");
    ^
    omaPoikkeus.java:42: error: non-static variable this cannot be referenced from a static context
    throw new SuuriPoikkeus("Luku on yli 10.");
    ^
    4 errors
    Process javac exited with code 1
    Last edited by E.K.Virtanen; April 25th, 2013 at 06:25 AM. Reason: solved


  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Problem to learn exceptions.

    Quote Originally Posted by E.K.Virtanen View Post
    What is the tree where im bangin my head currently?
    You tell us. What does this code do? Does it generate any compiler errors? Runtime errors? Does it result in unexpected behavior? Something else? What *exactly* is the problem?
    Useful links: How to Ask Questions the Smart Way | Use Code Tags | Java Tutorials
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  3. #3
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    Default Re: Problem to learn exceptions.

    Sorry about mis-information. I added compiler errors as quote in first program.
    I thought the program is so small, that i would not need to explain it's purpose with my poor english. But ill try if it's necessary.

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: Problem to learn exceptions.

    required: String
    found: omaPoikkeus.PieniPoikkeus
    The method takes a String as its arg, but the code is calling it with an omaPoikkeus.PieniPoikkeus object.
    If you don't understand my answer, don't ignore it, ask a question.

  5. #5
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    Default Re: Problem to learn exceptions.

    Ok. It took few days (and championship of icehockey by my favorite hockey team) but i finally got it.

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