Java - 如何检查对象是否是类定义中的类的实例

Code:

public class Composite extends Component implements Iterable<Component>{

    private List<Component> caseComponents = new ArrayList<Component>();


    @Override
    public Iterator<Component> iterator(){
        return new CompIterator();
    }



    private class CompIterator implements Iterator{
        int index = 0;

        @Override
        public boolean hasNext(){
            if(index<caseComponents.size()){
                return true;
            }
            return false;
        }

        @Override
        public Object next() {
            if(this.hasNext()){
                return caseComponents.get(index++);
            }
            return null;
        }
    }


    public String breadthFirst() {
        Queue<Component> q = new LinkedList<Component>();
        StringBuilder stringRep = new StringBuilder();
        q.add(this);

        while(q.element()!=null){
            Component first = q.remove();
            System.out.println(first.name);

            for(Component c : first.caseComponents){
                q.add(c);
            }
        }
    }
public class Composite extends Componen