You will have to build your own parser, which can take an input
string like "5+10" or "6*3", and parse each token, obtaining operands and operators, then apply semantic logic to process those operators and operands - you're basically building a mini-grammar.
If your input strings are very simple, you can just hack something together using a StringTokenizer, looking for a number followed by a math symbol (+,-,/,*) and then another number; if you use an int code to signify the operator then you can write a switch statment to do the actual calculation. For example, say you can parse out the numbers 5 and 10, and the operator "+". Then your logic would be:
int op1 = getOp1(); //5
int op2 = getOp2(); //10
int operator = getOperator(); //let 1 = "+"
int result;
switch(operator){
case 1: result = op1 + op2;
case 2: result = op1 - op2;
case 3: result = op1 * op2;
case 4: result = op1 / op2;
}
For more complicated input strings, you'll have to read up on compiler/parser theory and build your own grammar. There's a book called "Building a parser in java" that might help you.
Good luck!
[ March 10, 2002: Message edited by: Rob Ross ]
[ March 10, 2002: Message edited by: Rob Ross ]
