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javaparsingmathif-statementint

Shorter solution to if,else if,else if


I'm looking for a way to shorten this code up and avoid repeating code and if statements. What I'm doing is creating a calculator that searches strings for operators "* / + - " and executes them accordingly. Any ideas?

if (exp.charAt(i) == '*') {
    newResult = Integer.parseInt(exp.substring(0, i)) * Integer.parseInt(exp.substring(i + 1, exp.length()));
    primeResult = newResult;
    System.out.println(primeResult);
} else if (exp.charAt(i) == '/') {
    newResult = Integer.parseInt(exp.substring(0, i)) / Integer.parseInt(exp.substring(i + 1, exp.length()));
    primeResult = newResult;
    System.out.println(primeResult);
} else if (exp.charAt(i) == '+') {
    newResult = Integer.parseInt(exp.substring(0, i)) + Integer.parseInt(exp.substring(i + 1, exp.length()));
    primeResult = newResult;
    System.out.println(primeResult);
} else if (exp.charAt(i) == '-') {
    newResult = Integer.parseInt(exp.substring(0, i)) - Integer.parseInt(exp.substring(i + 1, exp.length()));
    primeResult = newResult;
    System.out.println(primeResult);
}

Also, is there a solution to accept a string with more than 2 operands? i.e. 5 + 10 * 2 / 3


Solution

  • For changing the code you could use a switch statement and putting some of the redundant code before or after the switch.

    int left = Integer.parseInt(exp.substring(0,i));
    int right = Integer.parseInt(exp.substring(i+1,exp.length()));
    switch(exp.charAt(i)){
        case '*':
            primeResult = left * right;
            break;
        case '/':
            ...
            break;
        case '+':
            ...
            break;
        case '-':
            ...
            break;
        default:
            ... // Error Handling.
    }
    System.out.println(primeResult);