Array elements


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Thread: Array elements

  1. #1
    Join Date
    Oct 2006
    Posts
    2

    Array elements

    Hi!

    I am new here - and i signed up as i am at University studying computer science and need help with Java programming tasks.

    Any help will be appreciated. - I have a firm knowledge of basic concepts in Java.

    My task today is to build a method which will detect wether a given element is present within an array starting

    public boolean contains(Object [] a, Object x)

    and it will return true if and only if there is an element y in such that x.equals(y) returns true.

    Can you guys with me a bit of help with this.

    Thanks very much - Andy
    I learn best via example - which is why i have posted the question.

  2. #2
    Join Date
    Oct 2006
    Posts
    4

    Answer to your Question

    here u go:
    Code:
    public class TestObj {
      public static void main (String [] args)throws Exception{
    	  a ob0 = new a("a","b");
    	  a ob1 = new a("c","d");
    	  a ob2 = new a("e","f");
    	  a ob3 = new a("g","h");
    	  a ob4 = new a("i","j");
    	  a ob5 = new a("k","l");
    	  a ob6 = new a("m","n");
    	  a ob7 = new a("d","f");
    	  
    	  Object [] objArray = {ob0, ob1,ob2,ob3,ob4,ob5,ob6,ob7};
    	  System.out.println(contains(objArray,ob0));
    	  
      	}
    	 public static boolean contains(Object [] a, Object x) {
    		 boolean rvalue = false;
    		 for(int i = 0; i < a.length ; i++){
    			 if(a[i].equals(x)){
    				 rvalue = true;
    				 break;
    			 }
    		 }
    		 return rvalue;
    	 }
    }
    But remember you might have to override the equal methods for your objects to work properly.....i.e. how are the two objects Comparable, on what attributes ????
    example:

    Code:
    class a{
    	String fname="bla";
    	String lname="bloo";
    	public a(){
    		this.fname = "";
    	    this.lname = "";
    	}
    	
    	public a(String fname, String lname){
    		this.fname = fname;
    		this.lname = lname;
    		
    	}
    	public boolean equals(Object obj){
    		if(this.fname.equals(((a)obj).fname) && this.lname.equals(((a)obj).lname) )
    				return true;
    		else return false;
    	}
    }


    good luck
    Last edited by dreamz; 10-02-2006 at 09:59 PM. Reason: To complete the code

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