CODEWITHSUNDEEP
java
Pawan
Pawan

Reputation: 32321

How to check null condition for the boolean variable

I have a class as shown 

package com;

public class Person {
boolean registered;

public boolean isRegistered() {
    return registered;
}

public void setRegistered(boolean registered) {
    this.registered = registered;
}
}

The Data to Person Object will be set based on the Data present in DB . The problem is that for older records the registered filed is not present .

so i how can i test if the filed is present or not ??

package com;

public class Test {

    public static void main(String args[]) {
        Person per = new Person();

        if (per.isRegistered()) {

        }
    }

}

How can i check if the per.isRegistered() field is present or not for that Person Object ??

Upvotes: 3

Views: 27911

Answers (10)

Vitaliy Kulikov
Vitaliy Kulikov

Reputation: 288

You should use Optional

if (Optional.ofNullable(per.isRegistered()).orElse(false)) {
  // ...
}

Upvotes: 1

Subhrajyoti Majumder
Subhrajyoti Majumder

Reputation: 41200

boolean is primitive data type which can not be null, only can be true or false. But Boolean Object which is rapper of boolean data type, It could be null and Boolean.TRUE and Boolean.FALSE;

public class Person {
    Boolean registered;
    ...
}

...

Person per = new Person();

if (per.isRegistered()!=null ) {
    if(!per.isRegistered()){
         ...
    }else{
         ...
    }
}

Upvotes: 5

gd1
gd1

Reputation: 11403

You can use the Boolean (capital B) class which allows NULL values for references of its kind.

Alternatively, you can use an enum having three possible values: NOT_AVAILABLE, YES, NO. This has a clearer semantics and allows you to add other possible values later (if needed).

Upvotes: 1

zoom
zoom

Reputation: 1756

I don't really get what is on your mind. But if you want to handle a boolean whose values can be one of the following {true/false/null}, you should use a Boolean object with is a simple boolean wrapper, but it can take the null value (as every Java Object can be set to null).

Upvotes: 1

Thijmen Venus
Thijmen Venus

Reputation: 46

You have to extend the person class to use it in the test class. You also have to define the boolean.

Upvotes: 0

Christian Achilli
Christian Achilli

Reputation: 5707

Make the column nullable and use a Boolean instead of boolean. For the specific problem though, I think you can assume that if it is null the user is not registered.

Upvotes: 0

triclosan
triclosan

Reputation: 5714

boolean registered as field it's false by default. Moreover boolean not related to Object class but primitive value so can't be null at all.

Only one Null-pointer you may get here it's when per is null

Upvotes: 0

pillingworth
pillingworth

Reputation: 3238

You need a three state boolean; true, false and not there.

You can achieve this by using Boolean class instead of the primitive boolean and use null as the "not there" indicator.

Upvotes: 1

Grant Thomas
Grant Thomas

Reputation: 45083

boolean can't be null; you'd need to use (Boolean) or construct a composite type.

Upvotes: 3

T.J. Crowder
T.J. Crowder

Reputation: 1074188

The way your Person class is currently defined, you can't, because boolean (the primitive type) has no null value, only true and false.

You could use Boolean (the object equivalent), which can be null, Boolean.TRUE, or Boolean.FALSE.

But more likely you want to solve this at a deeper level. You've said you have data in your database for which this field isn't present. Are those records considered registered or not? Your class should reflect the answer to that question.

Upvotes: 6

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