Jobsheet 5 - Conditional Syntax 1

Operator

Operator is special symbols that used to operate data (operand). Kind of operator is Assignment Operator, Arithmatic Operator, Relational Operator and Logical Operator.

Assignment Operator

Arithmatic Operator (Binary and Unary)

Relational Operator

Logical Operator

Basic Conditional Syntax

if

if (condition) {
  statement;
  statement;
}

Example

import java.util.Scanner;

public class IfSyntax {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    System.out.print("Please input temperature: ");
    int temperature = sc.nextInt();

    if (temperature < 16) {
      System.out.println("Please wear your jacket!");
    }
  }
}

Output

if-else

if (condition) {
  statement;
  statement;
} else {
  statement;
}

Example

import java.util.Scanner;

public class IfElseSyntax {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Please input temperature: ");
        int temperature = sc.nextInt();

        if (temperature < 16) {
            System.out.println("Please wear your jacket!");
        } else {
            System.out.println("Please wear your cap!");
        }
    }
}

Output

switch-case

switch (condition) {
  case constant-1:
    statement;
    break;
  case constant-2:
    statement-2;
    break;
  ...
  ...
  case constant-n:
    statement-n;
    break;
  default:
    statement;
}

Example

import java.util.Scanner;

public class SwitchCaseSyntax {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Input the number: ");
        int number = sc.nextInt();

        switch (number) {
            case 1:
                System.out.println("It's Sunday");
                break;
            case 2:
                System.out.println("It's Monday");
                break;
            case 3:
                System.out.println("It's Tuesday");
                break;
            case 4:
                System.out.println("It's Wednesday");
                break;
            case 5:
                System.out.println("It's Thursday");
                break;
            case 6:
                System.out.println("It's Friday");
                break;
            case 7:
                System.out.println("It's Saturday");
                break;
            default:
                System.out.println("Your number is invalid!");
        }
    }
}

Output

Multiple Conditional Syntax

Experiment

Experiment 1

• Open your text editor (Sublime, Notepad++, VSCode or Atom)
• Create new file then give filename Number.java
• Create class Number
• Write main() function java

• Add external library Scanner

  import java.util.Scanner;
  

• Declare variable with name scanner and datatype is Scanner

  Scanner scanner = new Scanner(System.in);
  

• Create a variable with datatype integer, then give name number.

  int number;
  

• Then insert code below to receive input from user.

  System.out.print("Please input the number: ");
  number = scanner.nextInt();
  

• Create conditional structure to check the number is even or odd. We can use the remaining values from modulus by 2.

  if (number % 2 == 0) {
    System.out.println("Number " + number + " is even.");
  } else {
    System.out.println("Number " + number + " is odd.");
  }
  

• Compile the java file using javac command, then execute the program.

Experiment 2

• Open text editor (sublime, VSCode, Notepad++ or Atom)

• See the picture below!

  

• Create filename with name ProfitOrLoss.java

• Then create class with name ProfitOrLoss
• Write basic structure main() function
• Add import library Scanner

  import java.util.Scanner;
  

• Declare variable sc with datatype Scanner

  Scanner sc = new Scanner(System.in);
  

• Create two variables with datatype int and a variable String.

  int purchasePrice;
  int sellingPrice;
  String status = null;
  

• Insert code below to ask user input.

  System.out.print("Please input the purchase price: ");
  purchasePrice = sc.nextInt();
  System.out.print("Please input the selling price: ");
  sellingPrice = sc.nextInt();
  

• Create basic structure conditional to check profit or loss.

  if (sellingPrice > purchasePrice) {
    status = "Profit";
  } else {
    status = "Loss";
  }
  

• Add code below to display the output of status

  System.out.println("You're " + status);
  

• Compile using javac and then run the program!

Experiment 3

• Open text editor (Sublime, VSCode, Notepad++ or Atom)
• Create new filename Calculator.java
• Create classname Calculator
• Write basic main() function
• Add import library Scanner

  import java.util.Scanner;
  

• Declare sc as Scanner

• Create three variables with data type double and a variable with data type char. Then give the names as number1, number2, result and operator.

  double number1, number2, number3;
  char operator;
  

• Add code below to ask user input.

  System.out.print("Input first number: ");
  number1 = sc.nextDouble();
  System.out.print("Input second number: ");
  number2 = sc.nextDouble();
  System.out.print("Input operator (+ - * /): ");
  operator = sc.next().charAt(0);
  

• Create switch-case to calculate operation.

  switch (operator) {
    case '+':
      result = number1 + number2;
      System.out.println(number1 + " + " + number2 + " = " + result);
      break;
    case '-':
      result = number1 - number2;
      System.out.println(number1 + " - " + number2 + " = " + result);
      break;
    case '*':
      result = number1 * number2;
      System.out.println(number1 + " * " + number2 + " = " + result);
      break;
    case '/':
      result = number1 / number2;
      System.out.println(number1 + " / " + number2 + " = " + result);
      break;
    default:
      System.out.println("Wrong operator!");
  }
  

• Compile and execute the program!

Questions

1. Explain the purpose of keyword below!

   • else
   • break
   • default

2. Explain the purpose of syntax below:

   • operator = sc.next().charAt(0);
   • if (number % 2 == 0)

3. In the experiment 3 add feature to calculate remaining value using modulus operator %!

Assignment

1. Create the program that needs input two integer number, then display the max number into the screen!

2. Please see the picture of flowchart below!

   

   Create the program based on the flowchart!

3. Financial officer calculate salary of employees every end of month. Total salary based on basic pay, meal allowance, and transportation allowance.

   Total salary = basic pay + meal allowance + transportation allowance

   If the total salary received is more than equal to IDR 1.500.000,00 then the salary is cut by tax 5%, while employees with total salary below IDR 1.500.000,00 do not get tax. Create the program to help financial officer calculate the total salary!

4. Create the program to determine placement class of student. If the grade of midterm exam more than 90 or the grade of final exam is equals 100, then the student go to class A, other than that go to class B. (Input: name of student, grade midterm exam and grade final exam!).