ex7.java

来自「java编程思想第四版习题答案」· Java 代码 · 共 37 行

// holding/Ex7.java
// TIJ4 Chapter Holding, Exercise 7, page 406
/* Create a class, then make an initialized array of objects of your class
* Fill a List from your array. Create a subset of your List by using
* subList(), then remove this subset from your List.
*/
import java.util.*;
import static net.mindview.util.Print.*;

class Tester {
	public static int counter = 0;
	private int id = counter++;
	public String toString() { return String.valueOf(id); }
}

public class Ex7 {
	public static void main(String[] args) {
		Tester[] t = new Tester[10];
		for(int i = 0; i < t.length; i++)
			t[i] = new Tester();
		List<Tester> lt = new ArrayList<Tester>();
		for(Tester x : t) lt.add(x);
		print("list of Tester: " + lt);
		List<Tester> sub = lt.subList(2, 6);
		print("subList: " + sub);
		// produces run time ConcurrentModificationException:
		// lt.removeAll(sub);
		// so, first make copy, remove sub, re-assign lt:
		List<Tester> copy = new ArrayList<Tester>(lt);
		copy.removeAll(sub);
		print("copy: " + copy);
		lt = copy;
		print("list of Tester: " + lt);
	}
}