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With this i am not able to convert a string which cointains symbols like ( , - , / , *) to double or integer .

I am expecting to get the answer as integer and all with all solving inputed in the string.

Your every effort is greatly appreciated , Thank you

CodePudding user response：

You can do that by loop through each characters and check if it's the operator or not and use substring

Here is an example

public class Main {
    public static void main(String[] args) {
        String a = "112   221";
        double y = computeString(a);
        System.out.println(y);
    }

    public static double computeString(String a) {
        double y = 0;
        for (int i = 0; i < a.length(); i  ) {
            // if the character is an operator
            if (a.charAt(i) == ' ') {
                // get the first number before the operator and convert it to a double value
                // then assign it to the total value y
                // then get the second number after the operator and convert it to a double value
                // then add it to the total value y
                y =  Double.parseDouble(a.substring(0, i))   Double.parseDouble(a.substring(i   2, a.length()));
                // first substring(0, i) gets the first number before the operator
                // second substring(i   2) gets the second number after the operator
            }
        }
        return y;
    }
}

If you want to make it valid to symbol like '-', ' ', '*', '/' change the operator in if statement in the function or add another condition and apply the same logic as I demonstrate in the function :)

CodePudding user response：

You can use the rhino class and evaluate it as a Javascript string.

implementation Lib in Gradle by adding

implementation 'io.apisense:rhino-android:1.1.1' 

then you can use it by

Object result = null;

ScriptEngine engine = new ScriptEngineManager().getEngineByName("rhino");

if (engine == null) {
    throw new UnsupportedOperationException("JavaScript scripting engine not found");
}
try {
    result = engine.eval("5 5"); // <- you can use mathematics operations
} catch (Exception  e) {
    Log.i("e",e.toString());
}
Log.i("ResultData" , result.toString());  // will be print (10)
double val =  Double.parseDouble(result.toString());