added function calculate()

src/practice1.java

@@ -1,5 +1,38 @@
-public class helloWorld() {
+import java.util.ArrayList;
+import java.util.Scanner; //scanner
+
+class HelloWorld {
+    static void calculate(ArrayList<E> ENTRIES_LIST, String OPERATION) {
+		// Calculate length. 
+		int ENTRIES_LIST_LENGTH = LIST_ENTRIES.length;
+
+		if (ENTRIES_LIST_LENGTH > 0) {
+			// Create a placeholder for return result. 
+			float OPERATION_RESULT = ENTRIES_LIST.get(0);
+			
+			if (ENTRIES_LIST_LENGTH > 1) {
+				for (int ENTRY_CURRENT = 1; ENTRY_CURRENT < ENTRIES_LIST_LENGTH; ENTRY_CURRENT++) {
+					if (OPERATION == "+") {
+						OPERATION_RESULT += ENTRIES_LIST.get(ENTRY_CURRENT);
+					} else if (OPERATION == "-") {
+						OPERATION_RESULT -= ENTRIES_LIST.get(ENTRY_CURRENT);
+					};
+				};
+			};
+		};
+	};
+	
+	
 	public static void main(String[] args) {
-		System.out.println("Hello, world");
-	}
+        Scanner input = new Scanner(System.in);
+
+		// Initialize the input numbers. 
+		ArrayList NUMBERS_INPUT = new ArrayList();
+		// Ask the number. 
+		
+
+		System.out.println();
+		
+		System.out.println("Hello, World!");
+    }
 }