As you have seen, you can often provide an initial value for a field in its declaration:

public class BedAndBreakfast {     public static int capacity = 10;  //initialize to 10     private boolean full = false;  //initialize to false}

This works well when the initialization value is available and the initialization can be put on one line. However, this form of initialization has limitations because of its simplicity. If initialization requires some logic (for example, error handling or a for loop to fill a complex array), simple assignment is inadequate. Instance variables can be initialized in constructors, where error handling or other logic can be used. To provide the same capability for class variables, the Java programming language includes static initialization blocks.

Note: It is not necessary to declare fields at the beginning of the class definition, although this is the most common practice. It is only necessary that they be declared and initialized before they are used.