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Java Identifiers

Java Identifiers - OR import java.util/to import all...

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Java identifiers (e.g., variable names) Java identifiers consist of letters, digit, under score _ , and dollar sign $. They cannot begin with a digit. Java API (Application Programmer Interfaces) Specification -- It contains the list of all pre-defined Java classes in the Java libraries. (There is a link to API Specification from the course web site -> notes -> Java API Specification) API contains packages, and each packages contain classes. Examples of packages: java.lang package, java.util package, etc. java.lang package contains the String class, the System class, and so on. Notes: java.lang is always imported without an "import" statement. However, to use a class in any other package, you need to import it. import java.util.Scanner;
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Unformatted text preview: OR import java.util.*; //to import all classes in this package System.out System.out is a destination (object) to which we can send output. Commonly used methods are "print" and "println". In order to print out "Hello World" in a console, we can use a code: System.out.print("Hello World"); You can print out a primitive data type using "print" method as well as strings. To concatenate a string with a string, or a primitive data, you can use "+". For instance, int number = 10; System.out.print("The number is " + number); "println" method adds a carriage return at the end. Thus System.out.print("Hello World\n"); and System.out.println("Hello World"); will give the same result....
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Java Identifiers - OR import java.util/to import all...

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