Four ways to traverse ArrayList collection in java

ArrayList traversal: take out the data in the ArrayList collection

Method one: for loop

Method two: Enhanced for loop: foreach

Method 3: Iterator: Iterator

Method 4: ListIterator: Bidirectional iterator

Free video tutorial recommendations: java online tutorial

Examples are as follows:

/**
 * ArrayList遍历：取出ArrayList集合中的数据
 * ①：for循环
 * ②：增强for循环：foreach
 * ③：Iterator：迭代器
 * ④：ListIterator：双向迭代器
 */
public class Demo {
	public static void main(String[] args) {
		ArrayList list = new ArrayList();
		list.add("ArrayList");
		list.add("基于数组的集合");
		list.add(true);
		list.add('I');
		list.add("也可以保存对象");
		System.out.print("第1种方式：");
		for (int i = 0; i < list.size(); i++) {//for
			System.out.print(list.get(i) + "  ");//get():获取指定索引处的值
		}
		
		System.out.print("\n第2种方式：");
		for (Object object : list) {//foreach
			System.out.print(object + "  ");
		}
		
		System.out.print("\n第3种方式：");
		Iterator iterator = list.iterator();//Iterator：可以遍历集合的迭代器
		while(iterator.hasNext()) {//boolean hasNext():是否存在下一个元素
			System.out.print(iterator.next() + "  ");//E(Object) next():获得下一个元素的值
		}
		
		System.out.print("\n第4种方式：");
		ListIterator listIterator = list.listIterator();//ListIterator：可以遍历集合的双向迭代器
		while (listIterator.hasNext()) {//boolean hasNext():从左到右依次遍历  判断是否存在下一个元素
			System.out.print(listIterator.next() + "  ");//E(Object) next():获得下一个元素的值
		}
		
		/*while (listIterator.hasPrevious()) {
		//boolean hasPrevious():逆向 ==》从右到左依次遍历 判断是否存在前一个元素
			System.out.print(listIterator.previous()+"  ");//E(Object) previous():获得上一个元素的值
		}*/
	}
}

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