From 81f5effad83709f8ec4b45539a97a0ae8172b0ed Mon Sep 17 00:00:00 2001
From: Banana <banana@optimus.de>
Date: Thu, 31 May 2018 10:10:18 +0200
Subject: [PATCH] java read command line example

---
 .../read-commandline-arguments-from-file.java | 92 +++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 java/read-commandline-arguments-from-file.java

diff --git a/java/read-commandline-arguments-from-file.java b/java/read-commandline-arguments-from-file.java
new file mode 100644
index 0000000..3a81587
--- /dev/null
+++ b/java/read-commandline-arguments-from-file.java
@@ -0,0 +1,92 @@
+/**
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the COMMON DEVELOPMENT AND DISTRIBUTION LICENSE
+ * 
+ * You should have received a copy of the
+ * COMMON DEVELOPMENT AND DISTRIBUTION LICENSE (CDDL) Version 1.0
+ * along with this program.  If not, see http://www.sun.com/cddl/cddl.html
+ * 
+ * 2018 http://www.bananas-playground.net
+ *
+ */
+
+/**
+ * This is an example how to simulate / read command line arguments from a file
+ * It will use a comandline argument to point to the file to read from
+ * so some code is kinda duplicate since we need to read the commandline options
+ * twice.
+ *
+ * more about the commandline usage can be found here
+ * https://www.tutorialspoint.com/commons_cli/commons_cli_usage_example.htm
+ */
+
+public class Main {
+
+    public static void main(String[] args) {
+	    // command line options and parser
+        Options options = new Options();
+        CommandLineParser parser = new DefaultParser();
+        CommandLine cmdline;
+
+        // option for the commandline file
+        Option commandFile = Option.builder("cf")
+            .argName("FILENAME")
+            .longOpt("command-file")
+            .desc("Provide command line options read from a file")
+            .hasArg()
+            .build();
+        options.addOption(commandFile);
+    }
+
+    // this is kinda duplicate but we need the options first
+    // and then decide if there are options from a file
+    try {
+        cmdline = parser.parse(options, args);
+    }
+    catch (UnrecognizedOptionException e) {
+        HelpFormatter formatter = new HelpFormatter();
+        formatter.printHelp("example", options);
+
+        System.exit(1);
+        return;
+    }
+
+    // check if we use a command line file
+    if((cmdline != null) && cmdline.hasOption("cf") && (cmdline.getOptionValue("cf") != null && !cmdline.getOptionValue("cf").isEmpty() )) {
+        // now read the file and use the given input as the arguments
+
+        String fileContent = null;
+        String filePath = cmdline.getOptionValue("cf");
+
+        // check if file exists
+        File f = new File(filePath);
+        if(f.exists() && !f.isDirectory()) {
+            try {
+                fileContent = new String ( Files.readAllBytes( Paths.get(filePath) ) );
+            }
+            catch (IOException e) {
+                e.printStackTrace();
+
+                System.exit(1);
+            }
+        }
+
+        args = CommandLineUtils.translateCommandline(fileContent);
+
+        try {
+            cmdline = parser.parse(options, args);
+        }
+        catch (UnrecognizedOptionException e) {
+            HelpFormatter formatter = new HelpFormatter();
+            formatter.printHelp("example", options);
+
+            System.exit(1);
+            return;
+        }
+
+        // do something
+    }
+    else {
+        System.out.println("Please provide a parameter");
+    }
+}
-- 
2.39.5