I always get the last value of an arraylist of objects

List<items> boxes = new ArrayList<items>();
boxes.add(new items("1", 0.1f, 0.2f, 0.1f));
boxes.add(new items("2", 0.1f, 0.4f, 0.1f));
boxes.add(new items("3", 0.1f, 0.1f, 0.2f));
boxes.add(new items("4", 0.1f,0.1f, 0.3f));
boxes.add(new items("5", 0.2f, 0.1f, 0.1f));
boxes.add(new items("6", 0.1f, 0.1f, 0.1f));
boxes.add(new items("7", 0.2f, 0.3f, 0.1f));
boxes.add(new items("8", 0.1f, 0.3f, 0.1f));
boxes.add(new items("9", 0.2f, 0.2f, 0.2f));
 		 
for (items box: boxes){
    System.out.println();
    System.out.println("length:  " +box.dimension.get("length"));
    System.out.println("breadth:  " +box.dimension.get("breadth"));
    System.out.println("height:  " +box.dimension.get("height"));
}

// this is the items class: 

    import java.util.*;
    
    public class items {
    
    	String boxNumber;
    	public static Map<string,> dimension = new HashMap<string,>();
    	public double volume;
    
    	public items(float l, float b, float h) {
    		volume = l * b * h;
    		dimension.put("length", l);
    		dimension.put("breadth", b);
    		dimension.put("height", h);
    
    	}
    
    	public items(String boxName, float i, float j, float k) {
    		boxNumber = boxName;
    		volume = i * j * k;
    		dimension.put("length", i);
    		dimension.put("breadth", j);
    		dimension.put("height", k);
    
    	}
    
    	public static Map<string,> getDimension() {
    		return dimension;
    	}
    
    	public static void setDimension(Map<string,> dimension) {
    		items.dimension = dimension;
    	}
    
    	public items rotateBox() {
    
    		Set<string> keySet = this.dimension.keySet();
    		String[] sides = keySet.toArray(new String[3]);
    		dimension.put(sides[1],
    				dimension.put(sides[2], dimension.get(sides[1])));
    		dimension.put(sides[0],
    				dimension.put(sides[2], dimension.get(sides[0])));
    
    		return this;
    	}
    
    	public double getVolume() {
    		// TODO Auto-generated method stub
    		return dimension.get("length") * dimension.get("breadth")
    				* dimension.get("height");
    	}
    }

length:  0.2
breadth:  0.2
height:  0.2
length:  0.2
breadth:  0.2
height:  0.2
length:  0.2
breadth:  0.2
height:  0.2
length:  0.2
breadth:  0.2
height:  0.2
length:  0.2
breadth:  0.2
height:  0.2
length:  0.2
breadth:  0.2
height:  0.2
length:  0.2
breadth:  0.2
height:  0.2
length:  0.2
breadth:  0.2
height:  0.2
length:  0.2
breadth:  0.2
height:  0.2