Introducing final

A variable can be declared as final. Doing so prevents its contents from being. modified. This means that you must initialize a final variable when it is declared. (In this usage, final is similar to canst in C/C++.) For example•Subsequent parts of your program can now use FILE_OPEN, etc., as if they were constants; without fear that a value has been changed.  It is a common coding convention to choose all uppercase identifiers for final variables. Variables declared as final do not occupy memory on a per-instance basis: Thus: a final variable is essentially a constant. ” The keyword final can also be applied to methods, but its meaning is substantially different than when it is applied to variables. This second final is described in’ ‘the next chapter, when inheritance is described.

Arrays Revisited

Arrays were introduced earlier in this book, before classes had been discussed. Now
that you know about classes, an important point can be made about arrays they are
implemented as objects. Because of this, there is a special array attribute that you will want to take advantage of. Specifically, the size of an array-that is, the number of elements that .an array can hold-is found in its length instance variable. All arrays have this variable, and it will always should the size of the array. Here is a program that , demonstrates this property.You can put the length member to good use in many situations. For example, here’ is an improved version of the Stack class. As you might recall, the earlier versions of , this.class always created a ten-element stack. The following version lets you create , stacks of any size. The value of steak length is ‘used to prevent the stack from overflowing.

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