using bug finder plugin, I found this bugs but does not understand why it was seen as bug in the code. Does anybody know and give me proper explanation regarding these? Thanks.
Source Code - https://drive.google.com/open?id=1gAyHFcdHBShV-9oC5G7GeOtCGf7bXoso;
Patient.java:17 Patient.generatePriority() uses the nextDouble method of Random to generate a random integer; using nextInt is more efficient [Of Concern(18), Normal confidence]
public int generatePriority(){
Random random = new Random();
int n = 5;
return (int)(random.nextDouble()*n);
}
ExaminationRoom.java:25 ExaminationRoom defines equals and uses Object.hashCode() [Of Concern(16), Normal confidence]
public boolean equals(ExaminationRoom room){
if (this.getWaitingPatients().size() == room.getWaitingPatients().size()){
return true;
}
else {
return false;
}
}
ExaminationRoom.java:15 ExaminationRoom defines compareTo(ExaminationRoom) and uses Object.equals() [Of Concern(16), Normal confidence]
// Compares sizes of waiting lists
@Override
public int compareTo(ExaminationRoom o) {
if (this.getWaitingPatients().size() > o.getWaitingPatients().size()){
return 1;
}
else if (this.getWaitingPatients().size() < o.getWaitingPatients().size()){
return -1;
}
return 0;
}
Hospital.java:41 Bad month value of 12 passed to new java.util.GregorianCalendar(int, int, int) in Hospital.initializeHospital() [Scary(7), Normal confidence]
doctors.add(new Doctor("Hermione", "Granger", new GregorianCalendar(1988, 12, 10), Specialty.PSY, room102));
Person.java:29 Return value of String.toLowerCase() ignored in Person.getFullName() [Scariest(3), High confidence]
public String getFullName(){
firstName.toLowerCase();
Character.toUpperCase(firstName.charAt(0));
lastName.toLowerCase();
Character.toUpperCase(lastName.charAt(0));
return firstName + " " + lastName;
}
First thing to remember about "bug finder" tools, is that they are usually only guidelines. With that said:
The class GregorianCalendar counts months from 0, meaning 0 is January, 11 is December. 12 represents the 13th month which doesn't exist. Since the function expects an int, and you gave it an int, no compiler error is generated, even though this is certainly a bug. This article does a good job explaining the reasons to upgrade, and give examples of how to use the new APIs: https://www.baeldung.com/java-8-date-time-intro
If in doubt, you can always check the documentation. In this case, the class Calendar (which GregorianCalendar extends) delcares a static constant public static final int JANUARY = 0; This confirms that january is indeed 0, but also indicates that we can use this constant in our code. You might find new GregorianCalendar(1988, Calendar.JANUARY, 10) to be a bit more readable.
You may also want to consider switching to the more modern and standard systems used to deal with time. The Java 8 Time libraries are the "new standard", and are definitely worth looking into.
Secondly, Strings are immutable in Java. This means that once a String is created, its value can never be changed. This may be counter to your intuitions, as you may have seen code such as:
String s = "hello";
s = s + " world";
However, this doesn't modify the string s. Instead, s + " world" creates a new String, and assigns it to the variable s.
Similarly, s.toLowerCase() doesn't change what s is, it only generates a new String which you must assign.
You probably want firstName = firstName.toLowerCase();
With your first example, nothing immediately jumps out to me as "bad", but if you look at the messages generated by your tool, they label the first example as "Of Concern", but label the others (e.g. the string.toLowerCase() example) as "Scary"/"Scariest". Although I am not familiar with this tool in particular, I imagine this is indicating more of a "Code Smell", rather than an actual bug.
Perhaps look into Unit Testing, if you want to reassure yourself that your code works.