キュー、およびループバッファ!

// 

public class Queue{
	public Object[] array;
	public int first,next;

	public static void main(String args[]){
	  Queue qu=new Queue();
	  /*
	  qu.first=0;
	  qu.next=5;  
	  */
      qu.first=2;
	  qu.next=1;
	  int a=5;
	  qu.add(a);
	  String b="abc";
	  qu.add(b);
	  System.out.println(qu.next);
	  while(!qu.isEmpty()){
	      System.out.println(qu.first+"  "+qu.remove());
	  }
	}

	public Queue(){
	  array=new Object[6];
	  first=0;
	  next=0;
	}

	public boolean isEmpty(){
	  return first==next;
	}

	public void add(Object item){
	  // 
	  if((next+1)%array.length==first)
		{  /*
		      
			  、next first ,array ,first,next 
			  、next first ,array ,first ,next 
		   */
	       if(next<first) 
			   next=(first+(array.length-1));
		   // 
           Object[] newArray=new Object[array.length*2];
		   array=newArray;
	  }
	  array[next]=item;
	  next=(next+1)%array.length;
	}

    public Object remove(){
	  // 
	  if(isEmpty()){
	    return null;
	  }else{
	  Object result=array[first];
	  //first++;
	  first=(first+1)%array.length;
	  return result;
	  }
	}
}

JDK 1のようです.4の