How to implement expression calculation Source Code in JAVA
This article mainly shows you "how to achieve the source code of expression calculation in JAVA", the content is easy to understand, clear, hope to help you solve your doubts, the following let Xiaobian lead you to study and learn "how to achieve expression calculation source code in JAVA" this article.
Operator supported: +-* /% > 0)
Return 1
Else
Return 0
}
Else if (opt.equals ("&")) {
If (dbValue1 > 0 & & dbValue2 > 0)
Return 1
Else
Return 0
}
Else if (opt.equals ("=")) {
If (dbValue1 = = dbValue2)
Return 1
Else
Return 0
}
} catch (Exception e)
{
Throw new ExpressionException ("value" + value1 + "or" + value2 + "is illegal when performing the" + opt + "operation!)
}
Throw new ExpressionException ("operator" + opt + "illegal!")
}
Protected String getValue (String oldValue) throws ExpressionException {
String reg = "^ ([a-zA-Z0-9] +) (([a-zA-Z0-9). ()] +) $"
If (this.isFunctionCal (oldValue)) {
Pattern p = Pattern.compile (reg)
Matcher m = p.matcher (oldValue)
M.find ()
Return calFunction (m.group (1), m.group (2))
}
Return oldValue
}
Protected boolean isFunctionCal (String value) {
String reg = "^ ([a-zA-Z0-9] +) (([a-zA-Z0-9). ()] +) $"
Return value.matches (reg)
}
Protected String calFunction (String function, String value) throws ExpressionException {
String lowerFun = function.toLowerCase ()
Double db = 0
Try
{
Db = Double.valueOf (this.getValue (value)) .doubleValue ()
If (lowerFun.equals ("log")) {
Return String.valueOf (Math.log (db))
}
Else if (lowerFun.equals ("square")) {
Return String.valueOf (Math.pow (db, 2))
}
Else if (lowerFun.equals ("sqrt")) {
Return String.valueOf (Math.sqrt (db))
}
Else if (lowerFun.equals ("sin")) {
Return String.valueOf (Math.sin (db))
}
Else if (lowerFun.equals ("asin")) {
Return String.valueOf (Math.asin (db))
}
Else if (lowerFun.equals ("cos")) {
Return String.valueOf (Math.cos (db))
}
Else if (lowerFun.equals ("tan")) {
Return String.valueOf (Math.tan (db))
}
Else if (lowerFun.equals ("atan")) {
Return String.valueOf (Math.atan (db))
}
Else if (lowerFun.equals ("ceil")) {
Return String.valueOf (Math.ceil (db))
}
Else if (lowerFun.equals ("exp")) {
Return String.valueOf (Math.exp (db))
}
} catch (Exception e)
{
Throw new ExpressionException ("function" + function + "value" + value + "illegal!")
}
Throw new ExpressionException ("function" + function + "not supported!")
}
Public static void main (String [] args)
{
BaseExpression be = new Base_Expression ()
String exp = "sin (ceil (sqrt (100) * 29" 20 "30" 3 "0 | 0 | 1" 1 "5" 2 "
Try
{
System.out.println (be.calculate (exp))
}
Catch (ExpressionException eE)
{
System.out.println (eE.getMessage ())
}
}
}
Expression exception class code:
Public class ExpressionException extends Exception {
Public ExpressionException (String msg)
{
Super (msg)
}
}
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