在我们使用try() catch(){}的时候,如果涉及到流操作,经常需要关闭流比如:
1 File file = new File("C:/Users/test.done"); 2 File newFile = new File(file.getAbsolutePath().replaceAll("\\.done$",".txt")); 3 BufferedReader bufferedReader = null; 4 BufferedWriter bufferedWriter = null; 5 String line = ""; 6 try { 7 bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(file))); 8 bufferedWriter = new BufferedWriter(new FileWriter(newFile)); 9 while ((line = bufferedReader.readLine()) != null) { 10 bufferedWriter.write(line+System.lineSeparator()); 11 } 12 } catch (Exception e) { 13 e.printStackTrace(); 14 } finally { 15 if(null != bufferedReader){ 16 try { 17 bufferedReader.close(); 18 } catch (IOException e) { 19 e.printStackTrace(); 20 } 21 } 22 if(null != bufferedWriter){ 23 try { 24 bufferedWriter.close(); 25 } catch (IOException e) { 26 e.printStackTrace(); 27 } 28 } 29 }
代码比较繁琐且很不方便,因此有简化的写法:
1 File file = new File("C:/Users/test.done"); 2 File newFile = new File(file.getAbsolutePath().replaceAll("\\.done$",".txt")); 3 String line = ""; 4 try(BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(file))); 5 BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(newFile));) { 6 while ((line = bufferedReader.readLine()) != null) { 7 bufferedWriter.write(line+System.lineSeparator()); 8 } 9 } catch (Exception e) { 10 e.printStackTrace(); 11 }
这种带资源的try语句(try-with-resource)在try块退出时,会自动调用bufferedReader.close()和bufferedWriter.close()方法,关闭资源,是不是很方便。
原文:https://www.cnblogs.com/qqq9527/p/12199949.html