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java - 如何在java中结束输入流

问题描述

我正在尝试使用 input.close() 关闭输入流，但我无法这样做。

              try {

        String line;
        Set<String> folderList = new HashSet<>();

        Process p = Runtime.getRuntime()
                .exec(new String[] { "cmd", "/K", "dir \"c:\\Program Files\\apache-tomcat-*\" /s" });

        BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));
        while ((line = input.readLine().trim()) != null) {
            if (line.contains("<DIR>")) {

                String folder = line.substring(line.indexOf("<DIR>") + "<DIR>".length()).trim();
                // System.out.println("c:\\Program Files" + "\\" + folder + "\\lib\\");
                String path = "c:\\Program Files" + "\\" + folder + "\\lib\\";
                folderList.add(folder);
                System.out.println(path);

            }

        }
        input.close();
        System.out.println("****");  // unreachable code error is I am not able to go out of the while loop.

提前致谢。

标签： java

解决方案

你可以把你的缓冲阅读器放在一个 try 子句中，它会自动关闭。

String line;
Set<String> folderList = new HashSet<>();
Process p = Runtime.getRuntime()
            .exec(new String[] { "cmd", "/K", "dir \"c:\\Program Files\\apache-tomcat-*\" /s" });


try(BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()))) {
    while ((line = input.readLine().trim()) != null) {
        if (line.contains("<DIR>")) {

            String folder = line.substring(line.indexOf("<DIR>") + "<DIR>".length()).trim();
            // System.out.println("c:\\Program Files" + "\\" + folder + "\\lib\\");
            String path = "c:\\Program Files" + "\\" + folder + "\\lib\\";
            folderList.add(folder);
            System.out.println(path);

        }
    }
    System.out.println("****"); 
} catch (IOException e) {
    e.printStackTrace();
}

此外，当返回 null(line = input.readLine().trim()) != null时有可能抛出 NullPointerException 。input.readLine()

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