How to convert string to operator in java

Question

I want to convert some String to an operator like this:

int value = 1;
int valueToCompare = 3;
String operation = \"<\";

if (value operation         


        

Answer 1

It is not directly possible, you'll have to write some code. One possibility is using enums:

enum Operation {
    LESS_THAN("<") {
        @Override int compare(int o1, int o2) {
            return o1 - o2;
        }
    },
    ...;

    private final String operator;
    private Operation(final String operator) {
        this.operator = operator;
    }

    private static final Map MAP = new HashedMap();
    static {
        for (final Operation op: values()) MAP.put(op.operator, op);
    }

    public static Operation valueOf(final String op) {
        return MAP.get(op);
    }
}

Usage example:

int cmp = Operation.valueOf(operation).compare(value, valueToCompare);