No, Constructors can be public, private, protected or default(no access modifier at all).
Making something private doesn't mean nobody can access it. It just means that nobody outside the class can access it. So private constructor is useful too.
One of the use of private constructor is to serve singleton classes. A singleton class is one which limits the number of objects creation to one. Using private constructor we can ensure that no more than one object can be created at a time.
Example -
public class Database {
private static Database singleObject;
private int record;
private String name;
private Database(String n) {
name = n;
record = 0;
}
public static synchronized Database getInstance(String n) {
if (singleObject == null) {
singleObject = new Database(n);
}
return singleObject;
}
public void doSomething() {
System.out.println("Hello StackOverflow.");
}
public String getName() {
return name;
}
}
More information about access modifiers.
