ArrayList 遍歷

1.迭代器遍歷

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.由於ArrayList實現了RandomAccess接口，全部支持隨即訪問。for 經過下標遍歷

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循環遍歷

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);
		}

	}
}

 

總結：

由於ArrayList是基於數組實現的，因此經過下標訪問速度是最快的。故推薦第二種方法進行集合遍歷