[ 
https://issues.apache.org/jira/browse/FLINK-10399?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16642051#comment-16642051
 ] 

ASF GitHub Bot commented on FLINK-10399:
----------------------------------------

TisonKun commented on a change in pull request #6737: [FLINK-10399] Refactor 
ParameterTool#fromArgs
URL: https://github.com/apache/flink/pull/6737#discussion_r223415555
 
 

 ##########
 File path: 
flink-java/src/main/java/org/apache/flink/api/java/utils/ParameterTool.java
 ##########
 @@ -68,81 +68,46 @@
         * @return A {@link ParameterTool}
         */
        public static ParameterTool fromArgs(String[] args) {
-               Map<String, String> map = new HashMap<String, 
String>(args.length / 2);
-
-               String key = null;
-               String value = null;
-               boolean expectValue = false;
-               for (String arg : args) {
-                       // check for -- argument
-                       if (arg.startsWith("--")) {
-                               if (expectValue) {
-                                       // we got into a new key, even though 
we were a value --> current key is one without value
-                                       if (value != null) {
-                                               throw new 
IllegalStateException("Unexpected state");
-                                       }
-                                       map.put(key, NO_VALUE_KEY);
-                                       // key will be overwritten in the next 
step
-                               }
-                               key = arg.substring(2);
-                               expectValue = true;
-                       } // check for - argument
-                       else if (arg.startsWith("-")) {
-                               // we are waiting for a value, so this is a - 
prefixed value (negative number)
-                               if (expectValue) {
-
-                                       if (NumberUtils.isNumber(arg)) {
-                                               // negative number
-                                               value = arg;
-                                               expectValue = false;
-                                       } else {
-                                               if (value != null) {
-                                                       throw new 
IllegalStateException("Unexpected state");
-                                               }
-                                               // We waited for a value but 
found a new key. So the previous key doesnt have a value.
-                                               map.put(key, NO_VALUE_KEY);
-                                               key = arg.substring(1);
-                                               expectValue = true;
-                                       }
-                               } else {
-                                       // we are not waiting for a value, so 
its an argument
-                                       key = arg.substring(1);
-                                       expectValue = true;
-                               }
+               final Map<String, String> map = new HashMap<>(args.length / 2);
+
+               final String errorMessage = "Error parsing arguments '%s' on 
'%s'.";
+
+               int i = 0;
+               while (i < args.length) {
+                       final String key;
+
+                       if (args[i].startsWith("--")) {
+                               key = args[i].substring(2);
+                       } else if (args[i].startsWith("-")) {
+                               key = args[i].substring(1);
                        } else {
-                               if (expectValue) {
-                                       value = arg;
-                                       expectValue = false;
-                               } else {
-                                       throw new RuntimeException("Error 
parsing arguments '" + Arrays.toString(args) + "' on '" + arg + "'. Unexpected 
value. Please prefix values with -- or -.");
-                               }
+                               throw new IllegalArgumentException(
+                                       String.format(errorMessage + " Please 
prefix keys with -- or -.",
+                                               Arrays.toString(args), 
args[i]));
                        }
 
-                       if (value == null && key == null) {
-                               throw new IllegalStateException("Value and key 
can not be null at the same time");
-                       }
-                       if (key != null && value == null && !expectValue) {
-                               throw new IllegalStateException("Value expected 
but flag not set");
-                       }
-                       if (key != null && value != null) {
-                               map.put(key, value);
-                               key = null;
-                               value = null;
-                               expectValue = false;
-                       }
-                       if (key != null && key.length() == 0) {
-                               throw new IllegalArgumentException("The input " 
+ Arrays.toString(args) + " contains an empty argument");
+                       if (key.length() == 0) {
+                               throw new IllegalArgumentException(
+                                       String.format(errorMessage + " Keys 
should never be empty",
+                                               Arrays.toString(args), 
args[i]));
                        }
 
-                       if (key != null && !expectValue) {
+                       i += 1; // try to find the value
+
+                       if (i >= args.length) {
+                               map.put(key, NO_VALUE_KEY);
+                       } else if (NumberUtils.isNumber(args[i])) {
+                               map.put(key, args[i]);
+                               i += 1;
+                       } else if (args[i].startsWith("--")) {
+                               map.put(key, NO_VALUE_KEY);
+                       } else if (args[i].startsWith("-")) { // negate number 
guarded by precondition
 
 Review comment:
   Thanks for the advice, address it.

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> Refactor ParameterTool#fromArgs
> -------------------------------
>
>                 Key: FLINK-10399
>                 URL: https://issues.apache.org/jira/browse/FLINK-10399
>             Project: Flink
>          Issue Type: Improvement
>          Components: Client
>    Affects Versions: 1.7.0
>            Reporter: TisonKun
>            Assignee: TisonKun
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.7.0
>
>
> {{ParameterTool#fromArgs}} uses a weird implement which flink developer would 
> fail to parse it fast.
> The main problem is that, when parse args, we always try to get a key-value 
> pair, but the implement iterate by a {{for}} loop, thus introduce weird 
> flag/mutable variable and branches.



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