CODEWITHSUNDEEP
javaoopbooleanboolean-logicunary-operator
Andrew Asmer
Andrew Asmer

Reputation: 11

Logical Complement Operator?

is it possible to use the logical operator "!" on object that holds a value of true or false? specifically for an object like this? 

public class Briefcase {
    private final double amount;
    private final String model;
    private boolean removed = false;
    private String face;

    public Briefcase(double amount, int face, String model) {
        this.face = Integer.toString(face);
        this.amount = amount;
        this.model = model;
    }

    public double getAmount() {
        return amount;
    }

    @Override
    public String toString() {
        return face;
    }

    public String getModel() {
        return model;
    }

    public void remove() {
        removed = true;
        face = "X";
    }

    public boolean isRemoved() {
        return removed;
    }
}

then use it like this 

Briefcase[] cases = new Briefcase[];
if (!cases[5].isRemoved()) { .... block of code}

is that possible? if so provide me links to that document that and some other examples, I find this weird at the same time interesting

Upvotes: 0

Views: 4960

Answers (5)

Romeo
Romeo

Reputation: 337

In this case ! negates the value of the call isRemoved() You can have a look here to see the list of operators: http://www.java-tips.org/java-se-tips/java.lang/what-is-java-operator-precedence.html

Also regarding the answer that said you can't write:

Briefcase[] cases = new Briefcase[];
if (!cases[5].isRemoved()) { .... block of code}

[] and . () operators have the same precedence.

The [] index operator will perform first because the line is evaluated from left to right, thus retrieving a Briefcase instance, on which you can call the isRemoved() method.

Upvotes: 0

sethu
sethu

Reputation: 8421

I am not sure whether you left the index in the array by mistake or design.. but this will definitely work:

if(!cases[i].isRemoved()){ .... block of code}

where i is the index.

Upvotes: 0

Johan Sjöberg
Johan Sjöberg

Reputation: 49187

The routine isRemoved only exist on the Briefcase object, not on the array. To use the negating operation ! you have to try something like the following 

for(BriefCase c: cases) {
    if (!c.isRemoved()) {
        // block of code
    }
}

Upvotes: 1

Matthias Meid
Matthias Meid

Reputation: 12523

It is. boolean is a primitive type, but I see nothing weird with using !.

Upvotes: 0

Suraj Chandran
Suraj Chandran

Reputation: 24791

Yes you can, but not with array as shown in code but as !case.isRemoved().

The point here is that !(negate operatior) works on boolean operands.

As long as the operand-expression resolves to a boolean ! this will work.

Upvotes: 0

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