ArrayList 遍历

1.迭代器遍历

package sourceCode.ArrayList;

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

public class arrayListTest {
	@SuppressWarnings({ "unchecked", "rawtypes" })
	public static void main(String[] args) throws Exception {
		List l = new ArrayList();
		for (int i = 0; i < 100; i++) {
			l.add(i + 1);
		}
		Iterator iterator = l.iterator();
		while (iterator.hasNext()) {
			System.out.println(iterator.next());
		}
	}
}

 

 

2.因为ArrayList实现了RandomAccess接口，所有支持随即访问。for 通过下标遍历

package sourceCode.ArrayList;

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

public class arrayListTest {
	 @SuppressWarnings({ "unchecked", "rawtypes" })
	public static void main(String[] args) throws Exception {
		List l =new ArrayList();
		for (int i = 0; i <100; i++) {
			l.add(i+1);
		}
		for (int i = 0; i<l.size(); i++) {
			System.out.println(l.get(i));
		}
		
	 }
	}

	

 

3.for循环遍历

package sourceCode.ArrayList;

import java.util.ArrayList;
import java.util.List;

public class arrayListTest {
	@SuppressWarnings({ "unchecked", "rawtypes" })
	public static void main(String[] args) throws Exception {
		List l = new ArrayList();
		for (int i = 0; i < 100; i++) {
			l.add(i + 1);
		}
		for (Object o : l) {
			System.out.println(o);
		}

	}
}

 

总结：

因为ArrayList是基于数组实现的，所以通过下标访问速度是最快的。故推荐第二种方法进行集合遍历