Java字符串和数学表达式求值程序 [英] Java String and Mathematical Expression Evaluators

问题描述

我们使用Jeks解析器来评估表达式。我看不到用它来评估字符串表达式的方法 - 例如：

IF（Test 1=Test 2） / p>

有没有什么可以评估Java中的字符串和数学表达式？感谢任何帮助，

Andez

解决方案

答案是在Jeks论坛上发贴。我得到了马努的回答。我以为它没有活跃，特别是因为我无法注册 - 但是它已被排序。

但是如果有任何人有同样的问题，那么以下代码行会得到它工作：

  ExpressionParser解析器; //我们做了=新的ExpressionParser（new JeksExpressionSyntax（），null）; 
 JeksInterpreter解释器// 
  

并创建解释器：

  interpreter = new JeksInterpreter（）{
 
 @Override 
 public Object getBinaryOperatorValue（Object binaryOperatorKey，Object param1，Object param2）
 { 
 //只有函数可以将单元格设置为参数
 if（param1 instanceof JeksCellSet || param2 instanceof JeksCellSet）
 throw new IllegalArgumentException（）; 
 //启用Jeks支持的类型之间的比较
 else if（binaryOperatorKey.equals（JeksExpressionSyntax.OPERATOR_EQUAL））
 return param1！= null&& param1.equals（param2）
？ Boolean.TRUE：Boolean.FALSE; 
 //启用Jeks支持的类型之间的比较
 else if（binaryOperatorKey.equals（JeksExpressionSyntax.OPERATOR_DIFFERENT））
 return param1！= null&& param1.equals（param2）？ Boolean.FALSE：Boolean.TRUE; 
 else 
 return super.getBinaryOperatorValue（binaryOperatorKey，param1，param2）; 
} 
}; 
 
 parser = new ExpressionParser（new JeksExpressionSyntax（），null）; 
  

We use the Jeks parser at present to evaluate expressions. I cannot see a way to evaluate string expressions with it - for example:

IF( "Test 1" = "Test 2")

Is there anything out there that can evaluate string and mathematical expressions in Java? Preferably free or open source.

Thanks for any help,

Andez

解决方案

The answer was a posting on the Jeks forum. I got an answer from Manu. I thought it was not active especially as I could not register on it - but that got sorted.

But if anyone has the same problem then the following lines of code will get it working:

ExpressionParser parser; // we did have = new ExpressionParser(new JeksExpressionSyntax(), null);
JeksInterpreter interpreter; // 

And to create the interpreter:

interpreter = new JeksInterpreter() {

      @Override
      public Object getBinaryOperatorValue (Object binaryOperatorKey, Object param1, Object param2)
      {
        // Only functions may take a cell set as parameter
        if ( param1 instanceof JeksCellSet || param2 instanceof JeksCellSet)
          throw new IllegalArgumentException ();
        // Enabled comparison between any type supported by Jeks
        else if (binaryOperatorKey.equals (JeksExpressionSyntax.OPERATOR_EQUAL))
          return param1 != null && param1.equals (param2)
                   ? Boolean.TRUE : Boolean.FALSE;
        // Enabled comparison between any type supported by Jeks
        else if (binaryOperatorKey.equals (JeksExpressionSyntax.OPERATOR_DIFFERENT))
          return param1 != null && param1.equals (param2) ? Boolean.FALSE : Boolean.TRUE;
        else
          return super.getBinaryOperatorValue (binaryOperatorKey, param1, param2);
      }
    };

    parser = new ExpressionParser(new JeksExpressionSyntax(), null);

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