重写ArrayList
import java.util.AbstractCollection; import java.util.Iterator; class ArrayListSon<E> extends AbstractCollection<E> { public String toString() { Iterator<E> i = iterator(); if (! i.hasNext()) return "[]"; StringBuilder sb = new StringBuilder(); sb.append('['); for (;;) { E e = i.next(); sb.append(e == this ? "(this Collection)" : e); if (! i.hasNext()) return sb.append(']').toString(); sb.append("| "); } } @Override public Iterator iterator() { // TODO Auto-generated method stub return null; } @Override public int size() { // TODO Auto-generated method stub return 0; } }
重写HashMap
import java.util.HashMap; import java.util.Iterator; import java.util.Map; class ListOrderedMapSon<E> extends HashMap{ //重写HashMapSon类的toString()方法 public String toString() { if (isEmpty()) { return "{}"; } StringBuffer buf = new StringBuffer(); buf.append('{'); boolean first = true; Iterator it = entrySet().iterator(); while (it.hasNext()) { Map.Entry entry = (Map.Entry)it.next(); Object key = entry.getKey(); Object value = entry.getValue(); if (first) first = false; else { buf.append("| "); } buf.append(key == this ? "(this Map)" : key); buf.append('='); buf.append(value == this ? "(this Map)" : value); } buf.append('}'); return buf.toString(); } }