if

if … else …

Simple Example

Question
Answer

Write a program to determine whether the body temperature entered by the user can be categorized as a fever

Input: body temperature in celcius (C)
Output: “Fever”, if body temperature is more than 37o C. If not, no outputs.

Program.java

  import java.util.*;
  public class Program {
      public static void main(String[] args) {
          Scanner in = new Scanner(System.in);
          double temperature = in.nextDouble();
          if (temperature > 37) { // condition
              System.out.println("Fever"); // Statements executed when the condition is true (fulfilled)
          }
      }
  }

Relational Operators

Operator	Description	Example
==	Equal to	x == y
!=	Not equal to	x != y
>	Greater than	x > y
<	Less than	x < y
>=	Greater than or equal to	x >= y
<=	Less than or equal to	x <= y

Logical Operators

Operator	Description	Example
&&	Logical AND	x && y
\|\|	Logical OR	x \|\| y
!	Logical NOT	!x

Example

x < 0 && y >= 10
number != 2 || number > 0
!(temperature > 37)
!(price < 10 || price > 100)
(width > 0 && width < 10) || (length > 20)

Chaining

if (condition1) {
// executed when condition1 is true
} else if (condition2) {
// executed when condition1 is false and condition2 is true
} else if (condition3) {
// executed when condition1 & 2 are false, condition3 is true
} else {
// executed when all conditions are false
}

Exercise

Exercise 1

Question
Answer

Write a program to calculate the total user must pay for an imported item.

If the price of the item exceeds USD 100, then an import tax of 20% is imposed
Input: price of items before tax in USD
Output: total paid (item price plus tax)

Program.java

  import java.util.*;
  public class Program {
      public static void main(String[] args) {
          Scanner in = new Scanner(System.in);
          double price = in.nextDouble();
          double tax = 0;
          if (price > 100) {
              tax = price * 0.2;
          }
          double total = price + tax;
          System.out.printf("The total paid is %.2f\n", total);
      }
  }

Exercise 2

Question
Answer

Write a program to determine whether the value entered by the user is odd or even.

Input: integer
Output: “Odd” or “Even”

Program.java

  import java.util.*;
  public class Program {
      public static void main(String[] args) {
          Scanner in = new Scanner(System.in);
          int number = in.nextInt();
          if (number % 2 == 0) {
              System.out.println("Even");
          } else {
              System.out.println("Odd");
          }
      }
  }

Exercise 3

Question
Answer

Write a program to determine whether the size of the baby at birth is normal or not

Normal baby weight at birth ranges from 2.5 to 4.5 kg and lengths between 45 and 60 cm
Input: baby’s weight in kg and length in cm
Output: whether the baby’s size is normal or not

Program.java

  import java.util.*;
  public class Program {
      public static void main(String[] args) {
          Scanner in = new Scanner(System.in);

          System.out.print("Enter the baby's weight: ");
          double weight = in.nextDouble();

          System.out.print("Enter the baby's length: ");
          double length = in.nextDouble();

          // Flag variables
          boolean normalWeight = (weight >= 2.5 && weight <= 4.5);
          boolean normalLength = (length >= 45 && length <= 60);

          if (normalWeight && normalLength) {
              System.out.println("Normal weight and length");
          } else if (normalWeight) {
              System.out.println("Normal weight, Abnormal length");
          } else if (normalLength) {
              System.out.println ("Abnormal weight, normal length");
          } else {
              System.out.println ("Abnormal weight and length");
          }
      }
  }

Exercise 4

Question
Answer

Write a program to convert grade in numbers to letters.

Conversion table:
Number Letter
< 41 E
41 to < 56 D
56 to < 61 C
61 to < 66 BC
66 to < 76 B
76 to < 81 AB
>= 81 A
Input: grade in number
Output: letter grade

Number	Letter
< 41	E
41 to < 56	D
56 to < 61	C
61 to < 66	BC
66 to < 76	B
76 to < 81	AB
>= 81	A

Program.java

  import java.util.*;
  public class Program {
      public static void main(String[] args) {
          Scanner in = new Scanner(System.in);

          System.out.print("Berapa nilaimu: ");
          double nilai = in.nextDouble();
          String nilaiHuruf;

          if (nilai < 41) {
              nilaiHuruf = "E";
          } else if (nilai < 56) {
              nilaiHuruf = "D";
          } else if (nilai < 61) {
              nilaiHuruf = "C";
          } else if (nilai < 66) {
              nilaiHuruf = "BC";
          } else if (nilai < 76) {
              nilaiHuruf = "B";
          } else if (nilai < 81) {
              nilaiHuruf = "AB";
          } else {
              nilaiHuruf = "A";
          }

          System.out.println("Nilai Huruf = " + nilaiHuruf);
      }
  }

Persiapan Belajar

Materi

Task

Programming by Doing

Compiler

Conditionals and Logic

if

if … else …

Simple Example

Relational Operators

Logical Operators

Chaining

Exercise

Exercise 1

Exercise 2

Exercise 3

Exercise 4

​if

​if … else …

​Simple Example

​Relational Operators

​Logical Operators

​Chaining

​Exercise

​Exercise 1

​Exercise 2

​Exercise 3

​Exercise 4

if

if … else …

Simple Example

Relational Operators

Logical Operators

Chaining

Exercise

Exercise 1

Exercise 2

Exercise 3

Exercise 4