concatenation method for array+varargs

src/de/uni_passau/fim/seibt/gitwrapper/process/ProcessExecutor.java

@@ -2,9 +2,11 @@ package de.uni_passau.fim.seibt.gitwrapper.process;
 
 import java.io.File;
 import java.io.IOException;
+import java.util.Arrays;
 import java.util.Optional;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import java.util.stream.Stream;
 
 import org.apache.commons.io.IOUtils;
 
@@ -42,12 +44,7 @@ public class ProcessExecutor {
             return exec(workingDir, redirectError, cmd);
         }
 
-        String[] cmdArray = new String[parameters.length + 1];
-
-        cmdArray[0] = cmd;
-        System.arraycopy(parameters, 0, cmdArray, 1, parameters.length);
-
-        return exec(workingDir, redirectError, cmdArray);
+        return exec(workingDir, redirectError, merge(false, parameters, cmd));
     }
 
     /**
@@ -92,8 +89,8 @@ public class ProcessExecutor {
             ExecRes res = new ExecRes();
             Process p = builder.start();
 
-            res.output = IOUtils.toString(p.getInputStream());
             res.exitCode = p.waitFor();
+            res.output = IOUtils.toString(p.getInputStream());
 
             LOG.fine(() -> String.format("Execution of '%s' returned exit code %d.", cmd, res.exitCode));
             LOG.finest(() -> String.format("Execution of '%s' output:%n%s", cmd, res.output.trim()));
@@ -104,4 +101,33 @@ public class ProcessExecutor {
             return Optional.empty();
         }
     }
+
+    /**
+     * Returns an array representing the concatenation of <code>arr</code> and <code>varArgs</code> in the order defined
+     * by <code>av</code>. If one of <code>arr</code> and <code>varArgs</code> is null, the other one is returned.
+     *
+     * @param av
+     *         if true returns [arr] + [varArgs] otherwise returns [varArgs] + [arr]
+     * @param arr
+     *         the array
+     * @param varArgs
+     *         the variable number of arguments
+     * @return the concatenation
+     */
+    public static String[] merge(boolean av, String[] arr, String... varArgs) {
+
+        if (arr != null && varArgs == null) {
+            return arr;
+        } else if (arr == null && varArgs != null) {
+            return varArgs;
+        } else if (arr == null && varArgs == null){
+            throw new IllegalArgumentException("Both arr and varArgs are null!");
+        }
+
+        if (av) {
+            return Stream.concat(Arrays.stream(arr), Arrays.stream(varArgs)).toArray(String[]::new);
+        } else {
+            return Stream.concat(Arrays.stream(varArgs), Arrays.stream(arr)).toArray(String[]::new);
+        }
+    }
 }