CODEWITHSUNDEEP
javaif-statementdynamic
Safinn
Safinn

Reputation: 642

Dynamic If Condition from String expression

Here is an example of a string expression I am creating that I then want to use in the condition of an if statement.

public static String dynamicIf(String a, String b, String c){
    String expression = "";
    String[] list = {"one", "two", ""};

    if(!a.equals(""))
        expression += "a.equals(list[0])";

    if(!b.equals(""))
    {
        if(!expression.equals(""))
            expression += " && b.equals(list[1])";
        else
            expression += "b.equals(list[1])";
    }

    if(!c.equals(""))
    {
        if(!expression.equals(""))
            expression += " && c.equals(list[2])";
        else
            expression += "c.equals(list[2])";
    }

    //String[] splitExpression = expression.split(" && ");

    return expression;
}

So the function above creates a string which i would then like to use in the condition of an if statement. The result of the method running with these parameters:

dynamicIf("one","two","");

is

a.equals(list[0]) && b.equals(list[1])

How can I get this expression in a string to run within the condition of an if? I hope you understand. Thank you.

Upvotes: 1

Views: 9802

Answers (1)

Julian
Julian

Reputation: 1736

You can't do this in Java, as it is not an interpreted language. Instead, redesign your code. Something like this might get you on the right track:

public static boolean dynamicIf(String a, String b, String c) {

    final String[] list = {"one", "two", ""};

    boolean value = true;

    if (!a.isEmpty()) {
        value &= a.equals(list[0]);
    }

    if(!b.isEmpty()) {
        value &= b.equals(list[1]);
    }

    if (!c.isEmpty()) {
        value &= c.equals(list[2]);
    }

    return value;
}

This should give you the same results you're looking for. Example:

if (dynamicIf("one", "two", ""))      // true
if (dynamicIf("", "two", ""))         // true
if (dynamicIf("", "", ""))            // true
if (dynamicIf("one", "two", "three")) // false

Edit: This may or may not be what you're looking for. You've left a comment that added more context to the problem and makes me think otherwise, but your desired end result is still unclear.

Upvotes: 2

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