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Thread: Recursive Methods ; StringIndexOutOfBoundsException

  1. #1
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    Default Recursive Methods ; StringIndexOutOfBoundsException

    This is a code to count how many times a character appeared in a String...
    It has to be done recursively...
    import java.io.*;
    public class Methods{
    	public static void main(String args []) throws IOException{
    		InputStreamReader instream = new InputStreamReader(System.in);
    		BufferedReader br = new BufferedReader (instream);
    		System.out.println("Please insert a passage");
    		String passage = br.readLine();
    		System.out.println("Please insert character");
    		String crc = br.readLine();
    		char x = crc.charAt(0);
    		System.out.println("This passage has this character " + crccount(passage, x)); 
    	}
    	public static int crccount(String passage, char x){
    		int count = 0;
    		int z = passage.length();
    		if (z == 0){
    			return 0;
    		}
    		if (passage.charAt(z) == x){
    			count++;
    		}
    		return count + crccount(passage.substring(0, z-1), x);
    	}
    }

    RUNTIME:
    Please insert a passage
    medo
    Please insert character
    e
    Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 4
    at java.lang.String.charAt(String.java:686)
    at Methods.crccount(Methods.java:459)
    at Methods.main(Methods.java:451)


    Any suggestions?


  2. #2
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    Default Re: Recursive Methods ; StringIndexOutOfBoundsException

    change only 1 line
     
    package test;
     
    import java.io.*;
    public class Methods{
    	public static void main(String args []) throws IOException{
    		InputStreamReader instream = new InputStreamReader(System.in);
    		BufferedReader br = new BufferedReader (instream);
    		System.out.println("Please insert a passage");
    		String passage = br.readLine();
    		System.out.println("Please insert character");
    		String crc = br.readLine();
    		char x = crc.charAt(0);
    		System.out.println("This passage has this character " + crccount(passage, x)); 
    	}
    	public static int crccount(String passage, char x){
    		int count = 0;
    		int z = passage.length();
    		if (z == 0){
    			return 0;
    		}
                    else if (passage.charAt(z-1) == x){//just change this line 
    			count++;
    		}
    		return count + crccount(passage.substring(0, z-1), x);
    	}
    }
    I hope it will work

  3. The Following User Says Thank You to serdar For This Useful Post:

    Medo Almasry (July 18th, 2011)

  4. #3
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    Default Re: Recursive Methods ; StringIndexOutOfBoundsException

    THANKS ALOT MAN...
    I HONESTLY APPRECIATE IT...

  5. #4
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    Default Re: Recursive Methods ; StringIndexOutOfBoundsException

    I didn't notice charAt method starts at 0... Silly mistakes :@
    Thanks alot though

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