package com.yishan.foreach;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

/**
 * @Author yishan
 * @Date 2021/10/19 0019 13:23
 * @Version 1.0
 */
public class RemoveDemo {

	//併發修改異常
	public static void main(String[] args) {
		//會產生併發修改異常
		//ConcurrentModificationException_for();
		//ConcurrentModificationException_iter();

		//不會產生併發修改異常
		//iteratorRemove();
		//CopyOnWriteArrayList();
	}

	/**
	 * CopyOnWriteArrayList 不會產生併發修改異常
	 */
	private static void CopyOnWriteArrayList() {
		List<String> list = new CopyOnWriteArrayList<>();

		for (int i = 0; i < 10; i++) {
			list.add(i + "");
		}
		System.out.println(list);

		Iterator<String> iterator = list.iterator();
		while (iterator.hasNext()) {
			String str = iterator.next();
			if ("5".equals(str)) {
				list.remove(5);
			}
		}
		System.out.println(list);
	}

	/**
	 * iterator.remove()方法可在迭代器遍歷中刪除元素
	 */
	private static void iteratorRemove() {
		List<String> list = new ArrayList<>();

		for (int i = 0; i < 10; i++) {
			list.add(i + "");
		}
		System.out.println(list);

		Iterator<String> iterator = list.iterator();
		while (iterator.hasNext()) {
			String str = iterator.next();
			if ("5".equals(str)) {
				iterator.remove();
			}
		}
		System.out.println(list);
	}

	/**
	 * 迭代器
	 */
	private static void ConcurrentModificationException_iter() {
		List<String> list = new ArrayList<>();

		for (int i = 0; i < 10; i++) {
			list.add(i + "");
		}
		System.out.println(list);

		Iterator<String> iterator = list.iterator();
		while (iterator.hasNext()) {
			String str = iterator.next();
			if ("5".equals(str)) {
				list.remove(5);
			}
		}
		System.out.println(list);
	}

	/**
	 * 增強for遍歷
	 */
	private static void ConcurrentModificationException_for() {
		List<String> list = new ArrayList<>();

		for (int i = 0; i < 10; i++) {
			list.add(i + "");
		}
		System.out.println(list);

		for (String o : list) {
			if ("5".equals(o)) {
				list.remove(5);
			}
		}
		System.out.println(list);
	}

}