String[] str = new String[] { "a", "b", "c" };

System.out.println(str);

System.out.println(str.toString());

控制台输出结果如下：

[Ljava.lang.String;@1db9742

[Ljava.lang.String;@1db9742

原因如下：

ArrayList继承AbstractList继承AbstractCollection

AbstractCollection实现Object类的toString方法。

 

public String toString() {        Iterator
     
       it = iterator();        if (! it.hasNext())            return "[]";        StringBuilder sb = new StringBuilder();        sb.append('[');        for (;;) {            E e = it.next();            sb.append(e == this ? "(this Collection)" : e);            if (! it.hasNext())                return sb.append(']').toString();            sb.append(',').append(' ');        }    }