This question already has an answer here: What is Double Brace initialization in Java? 11 answers It's called double curly brace initialization. (EDIT: Link removed, archived here) It means you're creating an anonymous subclass and the code within the double braces is basically a constructor. It's often used to add contents to collections because Java's syntax for creatin
这个问题在这里已经有了答案： 什么是Java中的Double Brace初始化？ 11个答案 它被称为双花括号初始化。 （编辑：链接删除，存档在这里） 这意味着你正在创建一个匿名子类，并且双花括号内的代码基本上是一个构造函数。 它通常用于向集合中添加内容，因为用于创建基本上集合常量的Java语法有些尴尬。 所以你可以这样做： List<String> list = new ArrayList<String>() {{ add("one"); add("two");
This question already has an answer here: How to efficiently iterate over each entry in a 'Map'? 38 answers From your code we can see the you are using countyData.get("pop") - ie you have hardcoded the key , so it will always return one and the same thing - the value associated with this key . PS: You can iterate over all the elements of the map, by using the keys form th
这个问题在这里已经有了答案： 如何有效地迭代'Map'中的每个条目？ 38个答案 从你的代码中，我们可以看到你使用的是countyData.get("pop") - 即你已经对key进行了硬编码，所以它总是会返回一个同样的东西 - 与这个key相关联的value 。 PS：您可以使用keySet的键遍历映射的所有元素： Set<KeyClass> keySet = myMap.keySet(); for(KeyClass key : keySet){ ValueClass value = myMap.get(key
Possible Duplicate: How do I iterate over each Entry in a Map? I'm following this solution to no effect: https://stackoverflow.com/a/1835742/666468 I am trying to output this Map: //protected Map<String,String> getImageTagAttributes() Image image = new Image(resource); for (Map<String, String> foo : image.getImageTagAttributes()) { String key = foo.getKey();
可能重复： 如何迭代Map中的每个条目？ 我遵循此解决方案无效：https://stackoverflow.com/a/1835742/666468 我正在尝试输出此地图： //protected Map<String,String> getImageTagAttributes() Image image = new Image(resource); for (Map<String, String> foo : image.getImageTagAttributes()) { String key = foo.getKey(); String value = foo.getValue(); //output here
This question already has an answer here: How to efficiently iterate over each entry in a 'Map'? 38 answers if (onLine != null) { for (String k : onLine.keySet()) { for (String v : onLine.get(k)) { out.print(v); } } } java.util.Map为此具有一个values（）方法： for(List<String> nextArray : onLine.values()) { for(String nextString : nextArra
这个问题在这里已经有了答案： 如何有效地迭代'Map'中的每个条目？ 38个答案 if (onLine != null) { for (String k : onLine.keySet()) { for (String v : onLine.get(k)) { out.print(v); } } } java.util.Map为此具有一个values（）方法： for(List<String> nextArray : onLine.values()) { for(String nextString : nextArray) { out.print(nextString);
Possible Duplicate: How do I iterate over each Entry in a Map? I make the personal profiles database,and I use HashMap to collect profile. private HashMap<String, Profile> database; but I want to write profile data to text files PrintWriter fileOut = new PrintWriter(new FileWriter(fileName)); fileOut.println(database.size()); for(int i = 0; i < database.size();i++){ Profile eac
可能重复： 如何迭代Map中的每个条目？ 我制作个人档案数据库，并使用HashMap收集档案。 private HashMap<String, Profile> database; 但我想将配置文件数据写入文本文件 PrintWriter fileOut = new PrintWriter(new FileWriter(fileName)); fileOut.println(database.size()); for(int i = 0; i < database.size();i++){ Profile eachProfile = database.get(key); } 但我不知道如何获得循环的关键字列表我
Possible Duplicate: How do I iterate over each Entry in a Map? How can I iterate over a map of <String, POJO>? I've written the following piece of code and am stuck on iterating over the hashmap. import java.util.ArrayList; import java.util.HashMap; import java.util.Iterator; import java.util.List; class demo { public static void main(String v[]) { ArrayList<Strin
可能重复： 如何迭代Map中的每个条目？ 我如何迭代<String，POJO>的地图？ 我写了下面这段代码，并且坚持迭代hashmap。 import java.util.ArrayList; import java.util.HashMap; import java.util.Iterator; import java.util.List; class demo { public static void main(String v[]) { ArrayList<String> contactIds = new ArrayList<String>(); contactIds.add("2"); c
Possible Duplicate: How do I iterate over each Entry in a Map? I am having a MAP, Map<String, Records> map = new HashMap<String, Records> (); public class Records { String countryName; long numberOfDays; public String getCountryName() { return countryName; } public void setCountryName(String countryName) { this.countryName = countryName;
可能重复： 如何迭代Map中的每个条目？ 我有一个MAP， Map<String, Records> map = new HashMap<String, Records> (); public class Records { String countryName; long numberOfDays; public String getCountryName() { return countryName; } public void setCountryName(String countryName) { this.countryName = countryName; } public long getNumberOfDa
This question already has an answer here: How to efficiently iterate over each entry in a 'Map'? 38 answers I'm sure there's some nice library that does this sort of thing already for you... But to just stick with the approach you're already going with, Map#entrySet gives you a combined Object with the key and the value . So something like: for (Map.Entry<String, Obj
这个问题在这里已经有了答案： 如何有效地迭代'Map'中的每个条目？ 38个答案 我确定有一些很好的库已经为你做了这样的事情......但是只要坚持你已经使用的方法， Map#entrySet会为你提供一个组合的Object其中包含key和value 。 所以像这样： for (Map.Entry<String, Object> entry : map.entrySet()) { System.out.println(entry.getKey() + ":" + entry.getValue().toString()); } 会做你以后的事情
Possible Duplicate: How do I iterate over each Entry in a Map? i have map like HashMap<Integer, ArrayList<String>> map = = new HashMap<Integer, ArrayList<String>>(); i want iterate this type of map please give me example how to iterate this map for (Map.Entry<String, ArrayList<String>> entry : map.entrySet()) { String key = entry.getKey(); ArrayL
可能重复： 如何迭代Map中的每个条目？ 我有地图 HashMap<Integer, ArrayList<String>> map = = new HashMap<Integer, ArrayList<String>>(); 我想迭代这种类型的地图，请给我例子如何迭代这张地图 for (Map.Entry<String, ArrayList<String>> entry : map.entrySet()) { String key = entry.getKey(); ArrayList<String> value = entry.getValue(); for(String aS
This question already has an answer here: How to efficiently iterate over each entry in a 'Map'? 38 answers If you need to add all the values in a Map , try this: float sum = 0.0f; for (float f : map.values()) { sum += f; } At the end, the sum variable will contain the answer. So yes, for traversing a Map 's values it's best to use a for loop. You can definitely do t
这个问题在这里已经有了答案： 如何有效地迭代'Map'中的每个条目？ 38个答案 如果您需要在Map添加所有值，请尝试以下操作： float sum = 0.0f; for (float f : map.values()) { sum += f; } 最后， sum变量将包含答案。 所以是的，为了遍历Map的值，最好使用for循环。 你绝对可以用for-loop来做到这一点。 您可以使用一个条目集： for (Entry<String, Float> entry : map.entrySet()) { sum +=