如何在哈希图中打印所有键? [英] How do I print out all keys in hashmap?

问题描述

我正在尝试了解哈希图的工作方式，并且一直在研究小型电话簿程序.

I'm trying to learn how hashmaps work and I've been fiddling with a small phonebook program.

但是当我想打印所有按键时，我很困惑.

But I'm stumped at what to do when I want to print out all the keys.

这是我的代码:

import java.util.HashMap;
import java.util.*;

public class MapTester
{

private HashMap<String, String> phoneBook;

public MapTester(){
   phoneBook = new HashMap<String, String>();
}

public void enterNumber(String name, String number){
   phoneBook.put(name, number);
}

public void printAll(){
    //This is where I want to print all. I've been trying with iterator and foreach, but I can't get em to work
}

   public void lookUpNumber(String name){
    System.out.println(phoneBook.get(name));
}
}

推荐答案

在这里:

System.out.println(phoneBook.keySet());

这将使用Set.toString()方法在Map中打印一组键.例如:

This will printout the set of keys in your Map using Set.toString() method. for example :

["a","b"]

这篇关于如何在哈希图中打印所有键?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！