linkedlistdictionary.java

not use Java API to produce two simple java implementation of a dictionary interface, LinkedListDict

package dict;

class Wrapper{
	public String key;
	public Object value;
	public Wrapper reference;
	public Wrapper(){
		reference=null;
	}
	public Wrapper(String k,Object v){
		key=k;
		value=v;
		reference=null;
	}
	public Wrapper(String k,Object v,Wrapper w){
		key=k;
		value=v;
		reference=w;
	}
}
public class LinkedListDictionary implements Dictionary{
	
	 protected Wrapper head,tail;
	 
	 public boolean isEmpty(){
	    	return head==null;
	    }
	    
     public void map(String key,Object value){ 
    	 if(!isEmpty()){
    		 tail.reference=new Wrapper(key,value);
    		 tail=tail.reference; 
    	 }
    	 else head=tail=new Wrapper(key,value);
     }
     
    
	 public Object find(String key){
		 Wrapper tmp=head;
		 for(;tmp!=null&&!key.equals(tmp.key);tmp=tmp.reference);
		 if(tmp==null)return null;
		 else return tmp.value;
	 }
	 
	 public Object delete(String key){
		 if(head!=null){
			 if(key.equals(head.key)&&(head.reference==null))
			   return head.value; 
			 if(key.equals(head.key)&&(head.reference!=null)){   
			   Wrapper tmp=head;
			   head=head.reference;
			   return tmp.value;}
			 else {
				 Wrapper pred=head,tmp=head.reference;
				 for(;tmp!=null&&!(tmp.key.equals(key));pred=pred.reference,tmp=tmp.reference);
				 if(tmp!=null){
				 pred.reference=tmp.reference;
				 return tmp.value;}
				 else return null;
			 }
		}
		 else return null;
	 }
	 
     public String toString(){
    	 String result="[";
    	 Wrapper pointer=head;
    	 for(;pointer!=null;pointer=pointer.reference){
    		 result+=(pointer.key+":"+pointer.value);
    		 if(pointer.reference!=null)result+=",";
    		 else result+="]";}
        return result;
     }
}