双向迭代器

package testBlog;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Set;
import java.util.TreeSet;

public class Test {
    public static void main(String[] args) {
        List<String> all = new ArrayList<>();
        all.add("abcdef");
        all.add("abcde");
        all.add("abcd");
        all.add("abc");
        
        ListIterator<String> iter = all.listIterator();//双向迭代器
        
        System.out.println("由前向后输出");
        while(iter.hasNext()) {
            String str = iter.next();
            System.out.println(str+",");
        }
        
        System.out.println("由后向前输出");
        while(iter.hasPrevious()) {
            String str = iter.previous();
            System.out.println(str+",");
        }

    }
}

结果:

由前向后输出
abcdef,
abcde,
abcd,
abc,
由后向前输出
abc,
abcd,
abcde,
abcdef,