Is it possble to convert a string in a/b format to double in Java? Ex: str = "4/5"; Can I parse this and get float/double value? I used parseDouble, but did not work and it expects something like "34.33" as input string.
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What you want is to evaluate the math expression and then parse the result to a double. There are libraries for evaluating a math expression in a string format, or you can write your own method for it. – Daniel B Aug 05 '14 at 08:26
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1This can help you: http://stackoverflow.com/questions/3422673/evaluating-a-math-expression-given-in-string-form – Athanor Aug 05 '14 at 08:26
3 Answers
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If your expression is always of the type "a/b" you can try something like:
String str = "4/5";
String parts[] = str.split("/");
double res = Double.parseDouble(parts[0])/Double.parseDouble(parts[1]);
Otherwise, use an expression evaluation tool as suggested in the comments above.
Pablo Francisco Pérez Hidalgo
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Use this :
String s = "35/6";
s = s.replace('/', '.');
double d = Double.parseDouble(s);
Saman Gholami
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1I think the OP wants to evaluate `4/5` and save its double value. You are proposing to use `/` as decimal separator token. I don't think that is right. Your code will result in `d = 35.6` whereas it should be `d = 5.83` – Pablo Francisco Pérez Hidalgo Aug 05 '14 at 08:32
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In javascript, you can use function "eval" to do it.But in Java,there is no function like that.So you use ScriptEngine to do it in java.
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine se = manager.getEngineByName("js");
String str = "4/5";
Double result =(Double) se.eval(str);
System.out.println(result);
userFromEast
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