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POLinked List get method using recursive method
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copied!<p>I was trying to design a get method for a linked list. It takes an int position as an argument and it returns the list element at the given position(position starts at zero).</p> <p>I think my logic is right, but doesn't compile. Could anyone point out what I have done wrong in here?</p> <pre><code>abstract public class AbstractListNode { abstract public Object first ( ); abstract public AbstractListNode rest ( ); abstract public boolean isEmpty ( ); abstract public int size( ); abstract public Object get(int index); // Every other list-processing method goes here. } class NonemptyListNode extends AbstractListNode { private Object myFirst; private AbstractListNode myRest; // cons in Scheme. public NonemptyListNode (Object first, AbstractListNode rest) { myFirst = first; if (rest == null) { myRest = new EmptyListNode ( ); } else { myRest = rest; } } public NonemptyListNode (Object first) { this (first, new EmptyListNode ( )); } // car in Scheme. public Object first ( ) { return myFirst; } // cdr in Scheme. public AbstractListNode rest ( ) { return myRest; } public boolean isEmpty ( ) { return false; } public int size ( ) { return 1+myRest.size(); } public Object get(int index){ if(index+1 > this.size()) throw new IllegalArgumentException ("Out of Range"); else if(index == 0){ return myFirst; } else{ index = index-1; AbstractListNode l = this.myRest; l.get(index); } } } class EmptyListNode extends AbstractListNode { public EmptyListNode ( ) { } public Object first ( ) { throw new IllegalArgumentException ("There is no 'first' value stored in an EmptyListNode."); } public AbstractListNode rest ( ) { throw new IllegalArgumentException ("No elements follow an EmptyListNode."); } public boolean isEmpty ( ) { return true; } public int size( ) { return 0; } public Object get(int index){ throw new IllegalArgumentException ("Out of Range"); } } </code></pre>

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