JDK7之前 ``` FileWriter fw = null; try { fw = new FileWriter("test.txt"); fw.write("测试"); } catch (IOException e) { e.printStackTrace(); }finally { try { if (fw != null){ fw.close(); } } catch (IOException e) { e.printStackTrace(); } } ``` JDK7 ``` try-with-resource 语句，该语句确保了每个资源在语句结束时关闭。所谓的资源 （resource）是指在程序完成后，必须关闭的对 try (FileWriter fw = new FileWriter("test.txt");){ fw.write("测试"); }catch (IOException e){ e.printStackTrace(); } ``` JDK9 ``` FileWriter fw = new FileWriter("test.txt"); try (fw;){ fw.write("测试"); }catch (IOException e){ e.printStackTrace(); } ```