A private constructor is used in classes containing only static member as shown below −
class Demo {
// private constructor
private Demo() { }
public static a = 10;
}A singleton class has normal methods and you can call it using an instance.
To prevent multiple instances of the class, the private constructor is used.
Let us see an example −
Example
public class Singleton {
static Singleton a = null;
private Singleton() {
}
}