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RowSet Interface

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RowSet Interface

Set stores unique elements. HashSet — unordered, fast.

LinkedHashSet — insertion order.

TreeSet — sorted order.

Write one tiny example for RowSet Interface. Compile, print one result, and say the output out loud before you type.

Use RowSet Interface 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. RowSet Interface — duplicate A is ignored; size stays 2. Start from main, go line by line, and stop at each print. That output is the proof for RowSet Interface.

Exam tip

Pick Set type by: speed vs order vs sorted.

Example

import java.util.HashSet;
public class Main {
  public static void main(String[] args) {
    HashSet<String> set = new HashSet<>();
    set.add("A");
    set.add("B");
    set.add("A"); // ignored
    System.out.println(set.size()); // 2
    System.out.println(set.contains("B"));
  }
}

RowSet Interface — duplicate A is ignored; size stays 2.

Short notes

DefRowSet Interface is a Java idea you should explain with one small example.
RuleKnow the keyword / API used for RowSet Interface. Type a tiny Main and print one result.
RememberFor RowSet Interface, say the output before you code.
TrapRowSet Interface — only memorising the heading. No example, no trap.
Unique only
HashSet fast

import java.util.HashSet; public class Main { public static void main(String[] args) { HashSet<String> set = new HashSet<>(); set.add("A"); set.add("B"); set.add("A"); // ignored System.out.println(set.size()); // 2 System.out.println(set.contains("B")); } }

RowSet Interface

Example

Short notes

Questions

RowSet Interface

Example

Short notes

Questions