Question

I have this class

public class Model {    
    private String a;
    private String b;

    public synchronized String getA() {
        return a;
    }
    public synchronized void setA(String a) {
        this.a = a;
    }
    public synchronized String getB() {
        return b;
    }
    public synchronized void setB(String b) {
        this.b = b;
    }   
}

I try to get the value of a, and I know that by default this variable is initialize to null. But, is it possible that if I call the getA() method, afterwards this variable has the String "null" on it (not null but the String)? So a.equals("null") == true.

public static void main(String[] args) throws ParseException {      
Model m = new Model();
String test = m.getA();
m.getA().equals("null");//No Exception occurs

}

And in fact the code where I eval the String is part of an Android Application:

    mAirline = (Airline) extras.getSerializable("airline");     
    @SuppressWarnings("unused")
    String test = mAirline.getPhone(); //(1)
    String test2 = mAirline.getHref(); //(2)

If I check mAirline in (1) mAirline has it fields in null, but in (2) has some of them to “null” And my method for get is

    public synchronized String getPhone() {
    return phone;
}

Answer 1

No, with the code you showed us, it’s not possible that you automatically get the String "null".

Note, however, that some methods will convert null to "null". The most notable examples are PrintWriter.println() (as in System.out.println()) and String.valueOf().

System.out.println(null);
System.out.println("null".equals(String.valueOf(null)));

These line will print null (i.e. the 4 characters) and true respectively