史上最全Java面试题整理（附参考答案）

<span class="hljs-function"&gt;<span class="hljs-keyword"&gt;public <span class="hljs-keyword"&gt;static <span class="hljs-keyword"&gt;void <span class="hljs-title"&gt;main<span class="hljs-params"&gt;(String[] args) {
    showDirectory(<span class="hljs-keyword"&gt;new File(<span class="hljs-string"&gt;"/Users/nnngu/Downloads"));
}

<span class="hljs-function"&gt;<span class="hljs-keyword"&gt;public <span class="hljs-keyword"&gt;static <span class="hljs-keyword"&gt;void <span class="hljs-title"&gt;showDirectory<span class="hljs-params"&gt;(File f) {
    _walkDirectory(f,<span class="hljs-number"&gt;0);
}

<span class="hljs-function"&gt;<span class="hljs-keyword"&gt;private <span class="hljs-keyword"&gt;static <span class="hljs-keyword"&gt;void <span class="hljs-title"&gt;_walkDirectory<span class="hljs-params"&gt;(File f,<span class="hljs-keyword"&gt;int level) {
    <span class="hljs-keyword"&gt;if(f.isDirectory()) {
        <span class="hljs-keyword"&gt;for(File temp : f.listFiles()) {
            _walkDirectory(temp,level + <span class="hljs-number"&gt;1);
        }
    }
    <span class="hljs-keyword"&gt;else {
        <span class="hljs-keyword"&gt;for(<span class="hljs-keyword"&gt;int i = <span class="hljs-number"&gt;0; i < level - <span class="hljs-number"&gt;1; i++) {
            System.out.print(<span class="hljs-string"&gt;"t");
        }
        System.out.println(f.getName());
    }
}

}

<span class="cke_reset cke_widget_drag_handler_container"><img class="cke_reset cke_widget_drag_handler" title="点击并拖拽以移动" src="data:image/gif;base64,R0lGODlhAQABAPABAP///wAAACH5BAEKAAAALAAAAAABAAEAAAICRAEAOw==" alt="" width="15" height="15" data-cke-widget-drag-handler="1">

在Java 7中可以使用NIO.2的API来做同样的事情，代码如下所示：