refactoring code

Author: RanVaknin

.changes/next-release/feature-AWSSDKforJavav2-1408e5f.json

@@ -0,0 +1,6 @@
+{
+    "type": "feature",
+    "category": "AWS SDK for Java v2",
+    "contributor": "",
+    "description": "Adding a new method of constructing ARNs without exceptions as control flow"
+}

core/arns/src/main/java/software/amazon/awssdk/arns/Arn.java

@@ -149,112 +149,93 @@ public static Builder builder() {
      *
      * @param arn A string containing an ARN to parse.
      * @return An {@link Optional} containing the parsed {@link Arn} if valid, or empty if invalid.
+     * @throws IllegalArgumentException if the ARN contains empty partition or service fields
      */
     public static Optional<Arn> tryFromString(String arn) {
+        return parseArn(arn, false);
+    }
+
+    /**
+     * Parses a given string into an {@link Arn}. The resource is accessible entirely as a
+     * string through {@link #resourceAsString()}. Where correctly formatted, a parsed
+     * resource containing resource type, resource and qualifier is available through
+     * {@link #resource()}.
+     *
+     * @param arn - A string containing an Arn.
+     * @return {@link Arn} - A modeled Arn.
+     */
+    public static Arn fromString(String arn) {
+        return parseArn(arn, true).orElseThrow(() -> new IllegalArgumentException("ARN parsing failed"));
+    }
+
+    private static Optional<Arn> parseArn(String arn, boolean throwOnError) {
         if (arn == null) {
             return Optional.empty();
         }
 
         int arnColonIndex = arn.indexOf(':');
         if (arnColonIndex < 0 || !"arn".equals(arn.substring(0, arnColonIndex))) {
+            if (throwOnError) {
+                throw new IllegalArgumentException("Malformed ARN - doesn't start with 'arn:'");
+            }
             return Optional.empty();
         }
 
         int partitionColonIndex = arn.indexOf(':', arnColonIndex + 1);
         if (partitionColonIndex < 0) {
+            if (throwOnError) {
+                throw new IllegalArgumentException("Malformed ARN - no AWS partition specified");
+            }
             return Optional.empty();
         }
-
         String partition = arn.substring(arnColonIndex + 1, partitionColonIndex);
 
         int serviceColonIndex = arn.indexOf(':', partitionColonIndex + 1);
         if (serviceColonIndex < 0) {
+            if (throwOnError) {
+                throw new IllegalArgumentException("Malformed ARN - no service specified");
+            }
             return Optional.empty();
         }
         String service = arn.substring(partitionColonIndex + 1, serviceColonIndex);
 
         int regionColonIndex = arn.indexOf(':', serviceColonIndex + 1);
         if (regionColonIndex < 0) {
+            if (throwOnError) {
+                throw new IllegalArgumentException("Malformed ARN - no AWS region partition specified");
+            }
             return Optional.empty();
         }
         String region = arn.substring(serviceColonIndex + 1, regionColonIndex);
 
         int accountColonIndex = arn.indexOf(':', regionColonIndex + 1);
         if (accountColonIndex < 0) {
+            if (throwOnError) {
+                throw new IllegalArgumentException("Malformed ARN - no AWS account specified");
+            }
             return Optional.empty();
         }
         String accountId = arn.substring(regionColonIndex + 1, accountColonIndex);
 
         String resource = arn.substring(accountColonIndex + 1);
         if (resource.isEmpty()) {
+            if (throwOnError) {
+                throw new IllegalArgumentException("Malformed ARN - no resource specified");
+            }
             return Optional.empty();
         }
 
-
         Arn resultArn = builder()
-                  .partition(partition)
-                  .service(service)
-                  .region(region)
-                  .accountId(accountId)
-                  .resource(resource)
-                  .build();
+            .partition(partition)
+            .service(service)
+            .region(region)
+            .accountId(accountId)
+            .resource(resource)
+            .build();
 
         return Optional.of(resultArn);
     }
 
-    /**
-     * Parses a given string into an {@link Arn}. The resource is accessible entirely as a
-     * string through {@link #resourceAsString()}. Where correctly formatted, a parsed
-     * resource containing resource type, resource and qualifier is available through
-     * {@link #resource()}.
-     *
-     * @param arn - A string containing an Arn.
-     * @return {@link Arn} - A modeled Arn.
-     */
-    public static Arn fromString(String arn) {
-        int arnColonIndex = arn.indexOf(':');
-        if (arnColonIndex < 0 || !"arn".equals(arn.substring(0, arnColonIndex))) {
-            throw new IllegalArgumentException("Malformed ARN - doesn't start with 'arn:'");
-        }
-
-        int partitionColonIndex = arn.indexOf(':', arnColonIndex + 1);
-        if (partitionColonIndex < 0) {
-            throw new IllegalArgumentException("Malformed ARN - no AWS partition specified");
-        }
-        String partition = arn.substring(arnColonIndex + 1, partitionColonIndex);
-
-        int serviceColonIndex = arn.indexOf(':', partitionColonIndex + 1);
-        if (serviceColonIndex < 0) {
-            throw new IllegalArgumentException("Malformed ARN - no service specified");
-        }
-        String service = arn.substring(partitionColonIndex + 1, serviceColonIndex);
-
-        int regionColonIndex = arn.indexOf(':', serviceColonIndex + 1);
-        if (regionColonIndex < 0) {
-            throw new IllegalArgumentException("Malformed ARN - no AWS region partition specified");
-        }
-        String region = arn.substring(serviceColonIndex + 1, regionColonIndex);
-
-        int accountColonIndex = arn.indexOf(':', regionColonIndex + 1);
-        if (accountColonIndex < 0) {
-            throw new IllegalArgumentException("Malformed ARN - no AWS account specified");
-        }
-        String accountId = arn.substring(regionColonIndex + 1, accountColonIndex);
-
-        String resource = arn.substring(accountColonIndex + 1);
-        if (resource.isEmpty()) {
-            throw new IllegalArgumentException("Malformed ARN - no resource specified");
-        }
-
-        return Arn.builder()
-                  .partition(partition)
-                  .service(service)
-                  .region(region)
-                  .accountId(accountId)
-                  .resource(resource)
-                  .build();
-    }
-
     @Override
     public String toString() {
         return "arn:"