在Java中实现eval（） [英] ImplementIon of eval() in Java

问题描述

我的问题与Java中不存在函数eval（）的现象有关。在互联网上阅读了一些内容之后，我发现我能做的最好的事情就是创建自己的解析器作为Java函数。但是怎么做呢？我实际需要的是一个函数，它读取上面数组的第一列并一个接一个地返回所有这些值。但请注意，这些值是字符串存储在String数组中，因此是字符串，但它们代表不同类型的对象，比如X1，X2，X3，X3等。

My question has to do with the phenomenon of non existence of function eval() in Java. After a bit of reading on the Internet I found out that the best thing I could do is to create my own parser as a Java function. But how to do that? What I need actually is a function that reads the first column of the above array and returns one after another all these values. Note however that these values are Strings are stored in a String array, thus are Strings, however they represent objects of different types, say X1, X2, X3, X3, etc.

如果我设法读取这个字符串值，比如说x1，作为一个对象，比如说X1，我就可以用它来调用一些与对象有关的函数，比如x1.classifyInstance（等等等等等等等等... ）;

If I manage to read this String value, say x1, as an object, say X1, I will then be able to use it for calling some object-X1-related functions, like x1.classifyInstance(blah blah blah...);

希望有人知道如何解决这个问题...！

Hope someone here has any idea about how to solve this issue...!

编辑：这个帖子与我的第一篇文章这里！

This thread is close-connected with my first post here!

推荐答案

你可以使用 eval（） 方法按照noreferrer> ScriptEngine 类将String评估为javascript字符串

You can use the eval() method of ScriptEngine class to evaluate the String as javascript string

ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("js");        
Object result = engine.eval("4*5");
System.out.println("..result..."+String.valueOf(result));

结果= ..结果... 20.0

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