OnJava8-Examples/collectiontopics/Unsupported.java

// collectiontopics/Unsupported.java
// (c)2021 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Unsupported operations in Java collections
import java.util.*;

public class Unsupported {
  static void
  check(String description, Runnable tst) {
    try {
      tst.run();
    } catch(Exception e) {
      System.out.println(description + "(): " + e);
    }
  }
  static void test(String msg, List<String> list) {
    System.out.println("--- " + msg + " ---");
    Collection<String> c = list;
    Collection<String> subList = list.subList(1,8);
    // Copy of the sublist:
    Collection<String> c2 = new ArrayList<>(subList);
    check("retainAll", () -> c.retainAll(c2));
    check("removeAll", () -> c.removeAll(c2));
    check("clear", () -> c.clear());
    check("add", () -> c.add("X"));
    check("addAll", () -> c.addAll(c2));
    check("remove", () -> c.remove("C"));
    // The List.set() method modifies the value but
    // doesn't change the size of the data structure:
    check("List.set", () -> list.set(0, "X"));
  }
  public static void main(String[] args) {
    List<String> list = Arrays.asList(
      "A B C D E F G H I J K L".split(" "));
    test("Modifiable Copy", new ArrayList<>(list));
    test("Arrays.asList()", list);
    test("unmodifiableList()",
      Collections.unmodifiableList(
        new ArrayList<>(list)));
  }
}
/* Output:
--- Modifiable Copy ---
--- Arrays.asList() ---
retainAll(): java.lang.UnsupportedOperationException
removeAll(): java.lang.UnsupportedOperationException
clear(): java.lang.UnsupportedOperationException
add(): java.lang.UnsupportedOperationException
addAll(): java.lang.UnsupportedOperationException
remove(): java.lang.UnsupportedOperationException
--- unmodifiableList() ---
retainAll(): java.lang.UnsupportedOperationException
removeAll(): java.lang.UnsupportedOperationException
clear(): java.lang.UnsupportedOperationException
add(): java.lang.UnsupportedOperationException
addAll(): java.lang.UnsupportedOperationException
remove(): java.lang.UnsupportedOperationException
List.set(): java.lang.UnsupportedOperationException
*/