Java · Theory

Static Nested Class

Theory

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Static Nested Class

Static Nested Class: inner/nested classes live inside another class. Static Nested Class is useful for helpers tightly coupled to the outer type.

Static Nested Class — anonymous class = one-off implementation.

Static Nested Class — static nested class does not need outer instance.

Write one tiny example for Static Nested Class. Compile, print one result, and say the output out loud before you type.

Use Static Nested Class only when the problem needs it. Don’t force it into every program. Know one beginner trap.

Let's take this on the board with one tiny Main class — no extra files. Static Nested Class — static nested Pair groups two ints with the outer Main type. Start from main, go line by line, and stop at each print. That output is the proof for Static Nested Class.

Exam tip

Give one real use: event listener / Comparator.

Example

public class Main {
  static class Pair {
    final int a, b;
    Pair(int a, int b) { this.a = a; this.b = b; }
  }
  public static void main(String[] args) {
    Pair p = new Pair(2, 3);
    System.out.println(p.a + p.b);
  }
}

Static Nested Class — static nested Pair groups two ints with the outer Main type.

Short notes

DefStatic Nested Class is a Java idea you should explain with one small example.
RuleKnow the keyword / API used for Static Nested Class. Type a tiny Main and print one result.
RememberFor Static Nested Class, say the output before you code.
TrapStatic Nested Class — only memorising the heading. No example, no trap.
Class inside class
Helper cohesion

public class Main { static class Pair { final int a, b; Pair(int a, int b) { this.a = a; this.b = b; } } public static void main(String[] args) { Pair p = new Pair(2, 3); System.out.println(p.a + p.b); } }

Static Nested Class

Example

Short notes

Questions

Static Nested Class

Example

Short notes

Questions