JAVA小练习126——增强for循环的练习

import java.util.HashSet;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeMap;

public class Demo126 {
	
	public static void main(String[] args) {
		HashSet<String>  set = new HashSet<String>();
		set.add("张三");
		set.add("李四");
		set.add("王五");
		
		System.out.println("===========迭代器的遍历方式===========");
		
		 Iterator<String> it = set.iterator();
		 //使用迭代器
		 while(it.hasNext()){ String
		 item = it.next(); 
		 System.out.print(item +","); //it.remove(); }
		 }
		 
		for(String item : set){  //遍历出来的每个元素都会交给item变量。
			System.out.print(item+",");
		
		}
		int[] arr = {19,17,18,30};
		
		//普通的for循环遍历
		for(int i = 0 ; i<arr.length ; i++){
			System.out.print(arr[i]+",");
		}
		
		
		//增强for循环
		for(int item :arr){
			System.out.print(item+",");
		}
		
		
		/*//在控制台打印5句hello world
		for(int i = 0 ; i<5; i++){
			System.out.println("hello world");
			*/
			
			int[] arr2 = new int[5];
			
			for(int item:arr2){
				System.out.println("hello world");
		}
		
			
			 TreeMap<Integer, String> tree = new TreeMap<Integer, String>(); 
			 
			 tree.put(110,"张三"); 
			 tree.put(109, "李四"); 
			 tree.put(120, "王五");
			 tree.put(115, "赵六");
			  
			 //使用增强for循环遍历map集合
			 Set<Entry<Integer, String>> entryes = tree.entrySet();
			 for(Entry<Integer, String> entry : entryes){
			 System.out.println("键："+entry.getKey()+" 值："+ entry.getValue()); }
			 
		
		
		
		
		
	
	}

}