Which package is automatically imported by the java system

This statement must be placed at the top of every source file. There can be only one such statement in each source file.

The Java source files must be placed in directories that match the package name. All types defined in the file with the above package are part of the com. A class Being has a fully qualified name com. There are millions of Java programmers worldwide. To avoid potential name conflicts, there is a naming convention in Java. The package names use reversed Internet domain names. The letters are written in lowercase. There can be only one zetcode.

A Java source file with a com. Package names are written in all lower case to avoid conflict with the names of classes or interfaces. The import keyword is used at the beginning of a source file to specify types classes, interfaces, enumerations, or annotations or entire Java packages to be referred to later without including their package names in the reference. Since Java SE 5. After this import, we can refer to all types of the java. The java. Java compiler automatically imports this package.

Java is a pure object oriented programming language where code is written in form of classes. These class components are called types.

Types in Java come in two flavours: built-in or primitive types and types from components. Primitive types can be used directly while component types must usually be ordered from a library by importing them from the appropriate package. The technical term for ordering a component from a library is bringing a component into scope. The Java standard libraries include java. Java is useless without much of the functionality in java.

However, one can import the same package or same class multiple times. There are situations where you need frequent access to static final fields constants and static methods from one or two classes. Prefixing the name of these classes over and over can result in cluttered code. The static import statement gives you a way to import the constants and static methods that you want to use so that you do not need to prefix the name of their class.

Math class defines the PI constant and many static methods, including methods for calculating sines, cosines, tangents, square roots, maxima, minima, exponents, and many more. You can use the static import statement to import the static members of java. Math so that you don't need to prefix the class name, Math.

The static members of Math can be imported either individually:. Once they have been imported, the static members can be used without qualification. For example, the previous code snippet would become:. Obviously, you can write your own classes that contain constants and static methods that you use frequently, and then use the static import statement.

All rights reserved. Hide TOC. The types that comprise a package are known as the package members. To use a public package member from outside its package, you must do one of the following: Refer to the member by its fully qualified name Import the package member Import the member's entire package Each is appropriate for different situations, as explained in the sections that follow. Note: Another, less common form of import allows you to import the public nested classes of an enclosing class.

For example, if the graphics. Rectangle class contained useful nested classes, such as Rectangle. DoubleWide and Rectangle.