12.grabbing floating point constants as input from keyboard in java.

Java is a general-purpose computer programming language that is concurrent, class-based, object-oriented,and specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "write once, run anywhere" (WORA), meaning that code that runs on one platform does not need to be recompiled to run on another.Java applications are typically compiled to bytecode that can run on any Java virtual machine (JVM) regardless of computer architecture. Java is, as of 2015, one of the most popular programming languages in use, particularly for client-server web applications, with a reported 9 million developers.Java was originally developed by James Gosling at Sun Microsystems (which has since merged into Oracle Corporation) and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++, but it has fewer low-level facilities than either of them.

Java is an object-oriented, cross platform, multi-purpose programming language produced by Sun Microsystems. First released in 1995, it was developed to be a machine independent web technology. It was based on C and C++ syntax to make it easy for programmers from those communities to learn. Since then, it has earned a prominent place in the world of computer programming.

Characteristics of java that have contributed to its popularity:
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Platform independence - Many languages are compatible with only one platform. Java was specifically designed so that it would run on any computer, regardless if it was running Windows, Linux, Mac, Unix or any of the other operating systems.

Simple and easy to use - Java's creators tried to design it so code could be written efficiently and easily.

Multi-functional - Java can produce many applications from command-line programs to applets to Swing windows (basically, sophisticated graphical user interfaces).

Java does have some drawbacks. Since it has automated garbage collection, it can tend to use more memory than other similar languages. There are often implementation differences on different platforms, which have led to Java being described as a "write once, test everywhere" system. Lastly, since it uses an abstract "virtual machine", a generic Java program doesn't have access to the Native API's on a system directly. None of these issues are fatal, but it can mean that Java isn't an appropriate choice for a particular piece of software.

There were five primary goals in the creation of the Java language.
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It must be "simple, object-oriented and familiar"

It must be "robust and secure"

It must be "architecture-neutral and portable"

It must execute with "high performance"

It must be "interpreted, threaded, and dynamic".

Primitive Types
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Primitive types are the most basic data types available within the Java language; these include boolean, byte, char, short, int, long, float and double. These types serve as the building blocks of data manipulation in Java. Such types serve only one purpose — containing pure, simple values of a kind. Because these data types are defined into the Java type system by default, they come with a number of operations predefined. You can not define a new operation for such primitive types. In the Java type system, there are three further categories of primitives:

Numeric primitives: short, int, long, float and double. These primitive data types hold only numeric data. Operations associated with such data types are those of simple arithmetic (addition, subtraction, etc.) or of comparisons (is greater than, is equal to, etc.)

Textual primitives: byte and char. These primitive data types hold characters (that can be Unicode alphabets or even numbers). Operations associated with such types are those of textual manipulation (comparing two words, joining characters to make words, etc.). However, byte and char can also support arithmetic operations.
Boolean and null primitives: boolean and null.