visual basic barcode program class FinalTest{ final int x; // Will work because it's initialized in the constructor in Java

Painting PDF417 in Java class FinalTest{ final int x; // Will work because it's initialized in the constructor

class FinalTest{ final int x; // Will work because it's initialized in the constructor
PDF 417 Reader In Java
Using Barcode Control SDK for Java Control to generate, create, read, scan barcode image in Java applications.
PDF 417 Generator In Java
Using Barcode generator for Java Control to generate, create PDF417 image in Java applications.
2: Declarations and Access Control
Read PDF-417 2d Barcode In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
Barcode Encoder In Java
Using Barcode creation for Java Control to generate, create barcode image in Java applications.
public FinalTest() { x = 28; // Whew! The compiler is relieved that we took care of it System.out.println("Final x = " + x); } }
Barcode Recognizer In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
PDF 417 Printer In C#
Using Barcode maker for .NET framework Control to generate, create PDF-417 2d barcode image in .NET applications.
So now we ve seen that you need to assign a value to a final variable, but then what As we mentioned earlier, you can t change a final variable once it s been initialized! Let s look at declaring an object reference variable as final:
Encode PDF417 In .NET Framework
Using Barcode encoder for ASP.NET Control to generate, create PDF 417 image in ASP.NET applications.
Creating PDF417 In .NET Framework
Using Barcode generation for .NET framework Control to generate, create PDF-417 2d barcode image in VS .NET applications.
import java.util.Date; class TestClass { final Date d = new Date(); public void showSample() { d.setYear(2001); //Altering Date object, not d variable, so it's OK } }
PDF-417 2d Barcode Generation In Visual Basic .NET
Using Barcode creator for Visual Studio .NET Control to generate, create PDF417 image in VS .NET applications.
Bar Code Printer In Java
Using Barcode generation for Java Control to generate, create bar code image in Java applications.
In the showSample() method in the preceding class, the year of the Date instance is modified by invoking setYear() on the final reference variable d. That s perfectly legal, and the class compiles fine, because an instance can have its data modified even though the reference to it is declared final. But now let s see what happens when we try to assign a new object to the final reference variable d, after d has been initialized.
Print Bar Code In Java
Using Barcode generator for Java Control to generate, create bar code image in Java applications.
GS1 DataBar Stacked Maker In Java
Using Barcode generator for Java Control to generate, create GS1 DataBar image in Java applications.
import java.util.Date; class FinalTest { final Date d = new Date(); // Initialize d public void showSample() { d.setYear(2001); d = new Date(); // Won't work! Can't change the value of d } }
ANSI/AIM I-2/5 Creator In Java
Using Barcode encoder for Java Control to generate, create 2/5 Interleaved image in Java applications.
Print 1D Barcode In .NET
Using Barcode encoder for .NET framework Control to generate, create 1D Barcode image in VS .NET applications.
Code within the showSample() method tries to reassign a new object to d. If we try to compile the preceding class, we re treated to this error:
Drawing GTIN - 128 In Objective-C
Using Barcode creator for iPhone Control to generate, create UCC-128 image in iPhone applications.
Printing UPC Code In None
Using Barcode encoder for Font Control to generate, create GTIN - 12 image in Font applications.
%javac FinalTest.java FinalTest.java:6: Can't assign a value to a final variable: d d = new Date(); 1 error
Make Barcode In Java
Using Barcode printer for Android Control to generate, create bar code image in Android applications.
Code 39 Full ASCII Scanner In C#.NET
Using Barcode decoder for .NET framework Control to read, scan read, scan image in VS .NET applications.
Declarations and Modifiers (Exam Objective 1.2)
Create GTIN - 12 In Visual Studio .NET
Using Barcode generation for ASP.NET Control to generate, create UPC-A Supplement 5 image in ASP.NET applications.
GTIN - 13 Printer In .NET Framework
Using Barcode encoder for ASP.NET Control to generate, create EAN / UCC - 13 image in ASP.NET applications.
Look for code that tries to reassign a final variable, but don t expect it to be obvious. For example, a variable declared in an interface is always implicitly final, whether you declare it that way or not! So you might see code similar to the following:
interface Foo { Integer x = new Integer(5); // x is implicitly final } class FooImpl implements Foo { void doStuff() { x = new Integer(5); // Big Trouble! Can t assign new object to x } }
The reference variable x is final. No matter what. You re allowed to explicitly declare it as final if you like, but it doesn t matter to the compiler whether you do or not. It simply is final, just because it s an interface variable, and they are always implicitly public static final. We ll look at interface variables again later in this chapter, but for now just remember that a final variable can t be reassigned, and that in the case of interface variables, they re final even if they don t say it out loud. The exam expects you to spot any attempt to violate this rule.
We ve now covered how the final modifier can be applied to classes, methods, and variables. Figure 2-6 highlights the key points and differences of the various applications of final. Transient Variables If you mark an instance variable as transient, you re telling the JVM to skip (ignore) this variable when you attempt to serialize the object declaring it. Serialization is one of the coolest features of Java; it lets you save (sometimes called flatten ) an object by writing its state (in other words, the value of its instance variables) to a special type of IO stream. With serialization you can save an object to a file, or even ship it over a wire for reinflating (deserializing) at the other end, in another JVM. For the exam, you aren t required to know how serialization works, but you need to know that transient can be applied only to instance variables. Don t be surprised, though, if serialization shows up in some future version of the exam. Regardless of its relevance for the exam, serialization is one of the most
Copyright © OnBarcode.com . All rights reserved.