在Java中创建地图 [英] Creating a map in Java

问题描述

我想要使​​用float（或double）键和char值创建一个地图。
我有：

  Map< double，char> memory = new HashMap< double，char>（）; 
  

但是，编译时返回错误。
错误是所有4种类型（左和右）的意外错误类型。
另一个错误说：type Map不采用参数
我如何解决这个问题？还是有更好的方法来制作字典？
谢谢David，

适应
现在的代码是：

  Map< Double，Character> memory = new HashMap< Double，Character>（）; 
  

它在名为GameLogic的类中。
但是，编译后会返回此错误消息：

  GameLogic.java:5：类型Map不使用参数
地图< Double，Character> memory = new HashMap< Double，Character>（）; 
  

扩展代码：

  public class GameLogic 
 {
 Map< Double，Character> memory = new HashMap< Double，Character>（）; 
 public static int position; 
 public static char currentBlock; 
 public static int currentGold; 
 public static int startingPosition; 
 
 
 
 public GameLogic（）
 {
 currentGold = 0; 
} 
 
 
 public void player_position（）
 {
 ... 
  

解决方案

像这样，在Java 5以上：

 地图< Double，Character> memory = new HashMap< Double，Character>（）; 
  

或者像这样，在Java 7及以上：

  Map< Double，Character> memory = new HashMap<>（）; 
  

在Java中，您不能创建基本类型的通用集合，因此您必须使用包装器类 - 所以 double 成为 Double ，而 char 成为code> Character 。

Im wanting to create a map with a float (or double) key and a char value. I have:

Map<double, char> memory = new HashMap<double, char>();

However this is returning errors when compiling. The errors are saying unexpected error type for all 4 types (left and right). Another error says: type Map does not take parameters How do I fix this? Or is there a better approach to making a dictionary? Thank you, David

Adapted The code is now:

Map<Double, Character> memory = new HashMap<Double, Character>();

It is in the class named GameLogic. But this returns this error message upon compiling:

GameLogic.java:5: type Map does not take parameters
Map<Double, Character> memory = new HashMap<Double, Character>();

Extended code:

public class GameLogic
{
    Map<Double, Character> memory = new HashMap<Double, Character>();
    public static int position;
    public static char currentBlock;
    public static int currentGold;
    public static int startingPosition;



public GameLogic()
{
    currentGold=0;
}


public void player_position()
{
...

解决方案

Like this, in Java 5 and up:

Map<Double, Character> memory = new HashMap<Double, Character>();

Or like this, in Java 7 and up:

Map<Double, Character> memory = new HashMap<>();

In Java you can't create a generic collection of primitive types, so you must use the wrapper classes - so double becomes Double, and char becomes Character.

这篇关于在Java中创建地图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！