PyQdeck LogoPyQdeckSubjectsSyllabusBlog

Introduction to Java · Introduction to Java Programming

Switch Statement

Watch lectures

Switch Statement

1. When to Use (beginner)

Switch = clean multi-choice for one variable against constants (day number → name). Cleaner than 7 if-else! Works on int, char, String, enum (not double/boolean!).

2. Classic Code (with break!)

int day = 3;
switch (day) {
    case 1: System.out.println("Mon"); break; // break STOPS fall-through!
    case 2: System.out.println("Tue"); break;
    case 3: System.out.println("Wed"); break;
    default: System.out.println("Invalid");   // catch-all (like else)
}
// Output: Wed

String switch (Java 7+):

String s = "red";
switch (s) {
    case "red": System.out.println("stop"); break;
    case "green": System.out.println("go"); break;
    default: System.out.println("?");
}

3. Fall-Through Trap (the famous exam bug!)

int x = 1;
switch (x) {
    case 1: System.out.print("one "); // NO break → falls!
    case 2: System.out.print("two "); // NO break → falls!
    default: System.out.print("other");
}
// Output: one two other (all three! — missing breaks!)

Grouping trick (intentional fall-through):

switch (ch) {
    case 'a': case 'e': case 'i': case 'o': case 'u':
        System.out.println("vowel"); break;
    default: System.out.println("consonant");
}

4. Traps

  • No break → falls through (most-asked output bug!).
  • switch on double/float/boolean/long = ERROR.
  • Modern arrow form (Java 14+): case 1 -> System.out.println("Mon"); (no fall-through!).

5. Exam Points

  • Day-name program + fall-through output — 5-7 marks, very frequent.
  • Allowed types + break role — 3 marks, frequent.
Free AppAndroid App

Coursify Android App

Generate AI courses, take quick quizzes between classes, and master complex engineering concepts on the go.

Install Coursify
Previous topicIf-Else StatementNext topicBreak Statement

← All Introduction to Java Programming modules