unsupported6.java

Thinking In Java 第四版练习题答案

// containers/Unsupported6.java
// TIJ4 Chapter Containers, Exercise 6, page 817
/* Note that List has additional "optional" operations that are not included
* in Collection. Write a version of Unsupported.java that tests these additional
* optional operations.
*/
import java.util.*;
import static org.greggordon.tools.Print.*;

public class Unsupported6 {
	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 subList:
		Collection<String> c2 = new ArrayList<String>(subList);
		try { c.retainAll(c2); } catch(Exception e) {
			println("retainAll(): " + e);
		}
		try { c.removeAll(c2); } catch(Exception e) {
			println("removeAll(): " + e);
		}
		try { c.clear(); } catch(Exception e) {
			println("clear(): " + e);
		}		 
		try { c.add("X"); } catch(Exception e) {
			println("add(): " + e);
		}
		try { c.addAll(c2); } catch(Exception e) {
			println("addAll(): " + e);
		}
		try { c.remove("C"); } catch(Exception e) {
			println("remove(): " + e);
		}
		// The List.set() method modifies the value but
		// doesn't change the size of the data structure:
		try {
			list.set(0, "X");
		} catch(Exception e) {
			println("List.set(): " + e);
		}
		// Additional optional List methods:
		try { list.add(0, "X"); } catch(Exception e) {
			println("List.add(): " + e);
		}
		try { list.addAll(0, c2); } catch(Exception e) {
			println("List.addAll(): " + e);
		}
		try { list.remove(0); } catch(Exception e) {
			println("List.remove(): " + e);
		}
		try { list.removeAll(c2); } catch(Exception e) {
			println("List.removeAll(): " + e);
		}
		try { list.retainAll(c2); } catch(Exception e) {
			println("List.retainAll(): " + e);
		}			
	}
	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("Modifiabe Copy", new ArrayList<String>(list));
		test("Arrays.asList()", list);
		test("unmodifiableLlist()", 
			Collections.unmodifiableList(new ArrayList<String>(list)));
	}
}