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lab/lab2/Question1/SumAndAverage.java

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+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-03-02
+ * Assignment: #1 Question 1
+ * Description: This program is used to calculate the sum and average of the numbers.
+ * Input: The numbers
+ * Output: The sum and average of the numbers
+ * Version: 1.0
+ */
+public class SumAndAverage {
+    public static void main(String[] args) {
+        int sum = 0; // Store the accumulated sum init to 0
+        double average; // average in double
+        int lowerbound = 1; // The lowerbound to sum
+        int upperbound = 100; // The upperbound to sum
+
+        // Use a for-loop to sum from lowerbound to upperbound
+        for (int number = lowerbound; number <= upperbound; number++) {
+            // add only odds number
+            if (number % 2 != 0) {
+                sum += number;
+            }
+        }
+
+        // Compute average in double. Beware that int/int produces int.
+        average = (double) sum / (upperbound - lowerbound + 1);
+
+        // Print sum and average
+        System.out.println("The sum is " + sum);
+        System.out.println("The average is " + average);
+
+        // 6.1 while loop
+        System.out.println("---- While-loop:");
+        sum = 0;
+        int number = lowerbound;
+        while (number <= upperbound) {
+            // only add number that is divisible by 7
+            if (number % 7 == 0) {
+                sum += number;
+            }
+            number++;
+        }
+
+        // Compute average in double. Beware that int/int produces int.
+        average = (double) sum / (upperbound - lowerbound + 1);
+
+        // Print sum and average
+        System.out.println("The sum is " + sum);
+        System.out.println("The average is " + average);
+
+        // 6.2 do-while
+        System.out.println("---- Do-while:");
+        sum = 0; // Reset sum
+        number = lowerbound;
+        do {
+            // sum of squares of number
+            sum += number * number;
+            number++;
+        } while (number <= upperbound);
+
+        // Compute average in double. Beware that int/int produces int.
+        average = (double) sum / (upperbound - lowerbound + 1);
+
+        // Print sum and average
+        System.out.println("The sum is " + sum);
+        System.out.println("The average is " + average);
+
+    }
+}

lab/lab2/Question2/TimeTable.java

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+/*
+ * Authro: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-03-02
+ * Description: A table of multiplication table of 1 to 9.
+ *     Using nested for loop to print the table.
+ * Assignemnt: #2 Question2
+ * Output:
+
+* |   1   2   3   4   5   6   7   8   9
+---------------------------------------
+1 |   1   2   3   4   5   6   7   8   9
+2 |   2   4   6   8  10  12  14  16  18
+3 |   3   6   9  12  15  18  21  24  27
+4 |   4   8  12  16  20  24  28  32  36
+5 |   5  10  15  20  25  30  35  40  45
+6 |   6  12  18  24  30  36  42  48  54
+7 |   7  14  21  28  35  42  49  56  63
+8 |   8  16  24  32  40  48  56  64  72
+9 |   9  18  27  36  45  54  63  72  81
+
+ */
+
+public class TimeTable {
+    public static void printHeader() {
+        System.out.println("* |   1   2   3   4   5   6   7   8   9");
+        System.out.println("---------------------------------------");
+    }
+    public static void printLineBegin(int i) {
+        System.out.print(i + " |");
+    }
+    public static int spaceBefore(int i) {
+        // format the number to be printed
+        String s = Integer.toString(i);
+        // calculate the number of spaces before the number
+        int len = s.length();
+        // return the number of spaces
+        int space = 4 - len;
+        return space;
+    }
+    public static void main(String[] args) {
+        // print the two lines header
+        printHeader();
+
+        // loop for main content
+        for (int i = 1; i <= 9; i++) {
+
+            printLineBegin(i);
+
+            // loop for each number in the line
+            for (int j = 1; j <= 9; j++) {
+                int number = i * j;
+
+                // print the space before the number
+                for (int k = 0; k < spaceBefore(number); k++) {
+                    System.out.print(" ");
+                }
+
+                // print the number
+                System.out.print(number);
+            }
+            // print the end of the line
+            System.out.println();
+        }
+    }
+}

lab/lab2/Question3/TestPalindrome.java

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+/*
+ * Author: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
+ * Date: 2022-03-02
+ * Description: Test whether a sentence is a palindrome, iguore the case punctuation and spaces.
+ * Assignment: #2 Question 3
+ */
+
+import java.util.Scanner;
+
+public class TestPalindrome {
+    public static void main(String[] args) {
+        System.out.print("Enter a String: ");
+        Scanner in = new Scanner(System.in);
+
+        // read a line of input from the user
+        String inStr = in.nextLine();
+
+        // close the scanner object
+        in.close();
+
+        // convert the string to lower case
+        String str = inStr.toLowerCase();
+
+        // remove all the punctuation using Character.isLetter()
+        // str = str.replaceAll("[^a-zA-Z0-9]", "");
+        String str2 = str;
+        str = "";
+        for (int i = 0; i < str2.length(); i++) {
+            if (Character.isLetter(str2.charAt(i))) {
+                str += str2.charAt(i);
+            }
+        }
+
+        // reverse the string
+        String reverse = new StringBuffer(str).reverse().toString();
+
+        // compare the two strings
+        // if they are the same, the string is a palindrome
+        // otherwise, it is not
+        System.out.format("\"%s\" is %s a palindrome.\n", inStr,
+                str.equals(reverse) ? "" : "not ");
+    }
+}