Java Academy · Lesson

Comparison & Logical Operators Deep Dive

Master comparison and logical operators, short-circuiting, precedence, and De Morgan's laws with practical patterns.

Lesson 1 of 38 steps

Comparison & Logical Operators Deep Dive is a free Java Academy lesson on CoddyKit. This is lesson 1 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Java Academy learning path, and your progress syncs across the web and the CoddyKit app. The Java Academy course includes 3 lessons in total.

Comparisons

Comparison operators

  • ==, !=: equal / not equal
  • <, >, <=, >=: ordering
  • Result is boolean (true or false).

Do not use == for Strings; use equals().

public class Main {
  public static void main(String[] args) {
    int x = 10;
    int y = 20;

    // Compare if x is less than y
    System.out.println(x < y);   // true (10 < 20)

    // Compare if x is equal to y
    System.out.println(x == y);  // false (10 is not equal to 20)

    // Extra examples:
    System.out.println(x > y);   // false (10 > 20? no)
    System.out.println(x != y);  // true  (10 is not equal to 20)
    System.out.println(x <= y);  // true  (10 <= 20)
    System.out.println(x >= y);  // false (10 >= 20? no)
  }
}

Logical Operators

Logical operators

  • && (and)
  • || (or)
  • ! (not)

They combine/negate boolean results. Example: (age >= 18 && country.equals("TR")).

Short-circuit

Short-circuit

  • a && b: if a is false, b is not evaluated.
  • a || b: if a is true, b is not evaluated.
  • Use this to guard checks that could fail (e.g., null checks).

Precedence

Precedence

  • Comparisons happen before && and ||.
  • && binds tighter than ||.
  • Use parentheses for clarity: (a > 0 && b > 0) || c > 0.

Patterns

De Morgan's laws

  • !(a && b) ≡ !a || !b
  • !(a || b) ≡ !a && !b

Range checks

  • 10 <= x && x <= 20 (inclusive)
  • x < 10 || x > 20 (outside)

Operators Demo

Try it: Enter values for x and y. Observe comparison results, combined conditions, and a short-circuit null guard.

public class Main {
  public static void main(String[] args) {
    // Instead of reading from Scanner, we assign fixed values
    int x = 12;
    int y = 5;

    boolean cmp1 = x < y;
    boolean cmp2 = x == y;
    boolean bothPositive = (x > 0 && y > 0);
    boolean eitherZero = (x == 0 || y == 0);
    boolean inRangeX = (10 <= x && x <= 20);

    System.out.println("x < y: " + cmp1);
    System.out.println("x == y: " + cmp2);
    System.out.println("bothPositive: " + bothPositive);
    System.out.println("eitherZero: " + eitherZero);
    System.out.println("10 <= x <= 20: " + inRangeX);

    // Short-circuit guard example
    String s = (x > 5) ? "big" : null;
    if (s != null && s.equals("big")) {
      System.out.println("s is big");
    }
  }
}

Short-circuit Check

Quick check: Which statements about short-circuit evaluation are true?

Recap & Next

Recap: You practiced comparisons, logical operators, short-circuiting, precedence, and De Morgan's laws.

Next: Use switch to select from multiple options more cleanly.

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Frequently Asked Questions

Is the “Comparison & Logical Operators Deep Dive” lesson free?

Yes — the full text of “Comparison & Logical Operators Deep Dive” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Java Academy course, upgrade to CoddyKit PRO. The Java Academy course includes 3 lessons in total.

What will I learn in “Comparison & Logical Operators Deep Dive”?

Master comparison and logical operators, short-circuiting, precedence, and De Morgan's laws with practical patterns. You practise Java Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Java Academy?

No prior experience is required. Java Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 1 of 3.

How long does the “Comparison & Logical Operators Deep Dive” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Java Academy lesson?

Yes. Every Java Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

  1. Comparison & Logical Operators Deep Dive
  2. Switch Statements
  3. Mini Project: Console Calculator
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