comparison operator objects in java

Question

Are there any object representation of these comparison operators (<, <=, ==, >=, >, !=) in Java ?

Eg use case:

void filterHotel( Object operator, float rating ) {

    String query = "SELECT hotel.name from hotel where hotel.rating " + 
operator.toString() + rating;    
    // execute query
}

Answer 1

No . But it is easy to write, consider using enum with custom method:

public enum Operator {
    EQUAL("=="),
    NOT_EQUAL("<>"),
    GREATER_THAN(">"),
    GREATER_THAN_OR_EQUAL(">="),
    LESS_THAN("<"),
    LESS_THAN_OR_EQUAL("<=");

    private final String representation;

    private Operator(String representation) {
        this.representation = representation;
    }

    public String getRepresentation() {
        return representation;
    }
}

Pass eg Operator.LESS_THAN and extract actual operator using operator.getRepresentation() .

Also make sure user cannot put arbitrary string in place of operator to avoid sql-injection .

Answer 2

There's nothing built in, but you can define an enum that does the trick:

public enum ComparisonOperator {
    LT("<"), LE("<="), EQ("=="), NE("<>"), GE(">="), GT(">");

    ComparisonOperator(String symbol) { this.symbol = symbol; }
    private final String symbol;
    public String toSymbol() { return symbol; }
}

Then:

void filterHotel(ComparisonOperator operator, float rating) {

    String query = "SELECT hotel.name from hotel where hotel.rating " + 
        operator.toSymbol() + rating;    
    // execute query
}