创建类的全局实例 - JAVA [英] Make global instance of class - JAVA

问题描述

在这段代码中，我试图创建类的全局实例，以便任何方法都可以使用它：

  public static void clip（）{
 while（！Display.isCloseRequested（））{
 glClear（GL_COLOR_BUFFER_BIT）; 
 
 if（character.gravity）character.y ++; //有错误，它说变量字符不存在
 Display.update（）; 
 Display.sync（70）; 
 
 
 
 public static void initGame（）{
 entity character = new entity（）; //我想在方法clip（）中使用它
 character.create（true，box，true）; 
} 
  

我搜索了google，但在我的问题中 什么都没发现。
感谢您的帮助。

解决方案

java中没有像全局变量那样的东西。

然而，你可以通过声明来声明字符作为类变量。 b
$ b

  entity character = new entity（）; 
  

以外的方法，仅限于类作用域。

类似的东西：

  class MyClass {
 private static entity character = new entity（）; //类变量！ （！！Display.isCloseRequested（））{
 glClear（GL_COLOR_BUFFER_BIT）; 
 public static void clip（）{
; 
 
 if（character.gravity）character.y ++; 
 Display.update（）; 
 Display.sync（70）; 
 
 
 
 public static void initGame（）{
 character = new entity（）; //它会'重置'游戏并将一个新对象绑定到类变量'character'。 
 character.create（true，box，true）; 
 
 
 code 
 $ b 
 有关类变量的更多信息可以在官方文档中。
 
 
作为一个边节点，一个类不应该被命名为 entity ，因为java有一个强大的约定，即类名应该总是以大写字母开头，您应该将此类重命名为实体。
 
In this code, I am trying to make global instance of class so any methods can use it:
public static void clip(){
    while(!Display.isCloseRequested()){
        glClear(GL_COLOR_BUFFER_BIT);

        if(character.gravity)character.y++; //there is an error, it says "Variable character does not exist"            
        Display.update();
        Display.sync(70);
    }
}

public static void initGame(){
    entity character = new entity(); // I want to use this in method clip()
    character.create(true, "box", true);
}
I've searched google, but on my question "Make instances of class global" found nothing.
Thanks for help.
解决方案
There is no such thing as a "global variable" in java.

However, you can declare character as a class variable by declaring:
entity character = new entity();
outside of methods, only on the class scope.

Something like that:
class MyClass { 
  private static entity character = new entity(); //class variable!
  public static void clip(){
      while(!Display.isCloseRequested()){
          glClear(GL_COLOR_BUFFER_BIT);

          if(character.gravity)character.y++; 
          Display.update();
          Display.sync(70);
      }
  }

  public static void initGame(){
      character = new entity(); // it will 'reset' game and bind a new object to the class variable `character`.
      character.create(true, "box", true);
  }
}
More info on class variables can be in the official documentation.



As a side node, a class should not be named entity, since java has a strong convention that classes names should always start with upper case letter, you should rename this class to Entity.

                        
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