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Summary - Operators

Combine arithmetic, comparison and logical operators to write a grade calculator.

Summary - Operators

In this group you learned Java operators:

  • Arithmetic: +, -, *, /, %
  • Comparison: ==, !=, <, >, <=, >=
  • Logical: &&, ||, !
  • Bitwise: &, |, ^, ~, <<, >>
  • Assignment/increment: =, +=, ++, --

Now combine them and write a grade calculator.

Practice Compute a grade

Write a Main class with a main method. Assign 60 to int midterm and 80 to int finalGrade. Assign (midterm + finalGrade) / 2 to int average. Print average with println.

Sample solution

Main.java
public class Main {
    public static void main(String[] args) {
        int midterm = 60;
        int finalGrade = 80;
        int average = (midterm + finalGrade) / 2;
        System.out.println(average);
    }
}

Expected output

70

Tips

A few tips from this group:

  • Integer division gives an integer; use double for decimals.
  • == compares, = assigns; do not mix them.
  • Use && and || for logic, & and | for bitwise.
  • ++x increments first, x++ increments after.
  • Use bitwise operators only when you really need them.

These basics are needed for conditionals and loops.

Practice Check status with logical and

Write a Main class with a main method. Assign 25 to int age. Assign age >= 18 && age <= 65 to boolean inRange. Print inRange with println.

Sample solution

Main.java
public class Main {
    public static void main(String[] args) {
        int age = 25;
        boolean inRange = age >= 18 && age <= 65;
        System.out.println(inRange);
    }
}

Expected output

true

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Match the operator families

Term Meaning
+, -, *, / Arithmetic
==, != Comparison
&&, || Logical
&, | Bitwise

2 Complete the comparison operator

Question 
boolean passed = average ____ 50;
Answer 
boolean passed = average >= 50;

Explanation: average >= 50 means passed.

All lessons in Beginner

1 Java basics

  1. What is Java?
  2. The main method
  3. Comments
  4. Class skeleton
  5. javac and java
  6. Summary - Java basics

2 Variables

  1. int and double
  2. boolean
  3. String
  4. Naming variables
  5. final variables
  6. Summary - Variables

3 Data types

  1. Primitive types
  2. Type casting
  3. String concatenation
  4. Math class
  5. BigInteger and BigDecimal
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add/subtract
  3. Multiply/divide
  4. Error handling
  5. Putting it together

5 Operators

  1. Arithmetic
  2. Comparison
  3. Logical
  4. Bitwise
  5. Assignment and increment
  6. Summary - Operators

6 String basics

  1. length and charAt
  2. equals and equalsIgnoreCase
  3. indexOf and substring
  4. toUpperCase and trim
  5. String.format
  6. Summary - String basics

7 Conditionals

  1. The if statement
  2. else and else if
  3. Nested if
  4. switch
  5. Ternary
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. do-while
  4. break and continue
  5. for-each
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding items
  3. Calculating totals
  4. Updating quantity
  5. Putting it together

10 Arrays

  1. Declaring arrays
  2. Array access
  3. Filling arrays
  4. Multi-dimensional arrays
  5. Copying arrays
  6. Summary - Arrays

11 Array methods

  1. Arrays.sort
  2. Arrays.toString
  3. Arrays.binarySearch
  4. Arrays.copyOf
  5. Arrays.fill
  6. Summary - Array methods

12 Collections

  1. ArrayList
  2. add and get
  3. HashMap
  4. put and get
  5. HashSet
  6. Summary - Collections

13 Methods

  1. Defining methods
  2. return
  3. void methods
  4. Method overloading
  5. Scope
  6. Summary - Methods

14 Method parameters

  1. Primitive parameters
  2. Object parameters
  3. varargs
  4. Multiple values via array
  5. final parameters
  6. Summary - Method parameters

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 String builder

  1. StringBuilder
  2. append
  3. insert and delete
  4. reverse
  5. toString
  6. Summary - String builder

17 Input and output

  1. Scanner
  2. nextInt and nextLine
  3. System.out.printf
  4. BufferedReader
  5. try-with-resources
  6. Summary - Input and output

18 Enum

  1. Declaring enums
  2. values and valueOf
  3. Enum fields
  4. Enum methods
  5. switch with enum
  6. Summary - Enum

19 Exception basics

  1. try/catch
  2. finally
  3. throw
  4. Exception hierarchy
  5. Multiple catch
  6. Summary - Exception basics

20 Beginner final

  1. Project design
  2. Data model
  3. Business logic
  4. Error handling
  5. Putting it together