Implemented Runtime.exec(String) and Runtime.exec(String[]) and added test class

test/RuntimeExec.java

@@ -0,0 +1,13 @@
+import java.lang.Runtime;
+
+public class RuntimeExec {
+  public static void main(String[] args) throws java.io.IOException {
+    System.out.println("Executing internet explorer");
+    Runtime.getRuntime().exec("\"c:\\program files\\internet explorer\\iexplore.exe\" http://www.google.com");
+    System.out.println("Executing firefox");
+    String[] firefox = new String[2];
+    firefox[0] = "c:\\program files\\mozilla firefox\\firefox.exe";
+    firefox[1] = "http://www.google.com";
+    Runtime.getRuntime().exec(firefox);
+  }
+}