What is Byte code in Java?

Java has lots of good features. Platform Independency is one of them. To implement Platform Independency Java uses the concept of Bytecode.

When Java source code(.java) compile, .class file produces. This .class file contains Bytecode. Java compiler does not take any kind of help of Operating System during generating .class. That's why Bytecode is a Platform Independent code.

Why it called Bytecode?
Let see one example first. Have you heard about Stenography? When in a Court, hearing goes, a person with a typewriter in a corner, type the whole hearing in real time. He uses some kind of symbols for long words and sentences and after hearing he decrypt the whole conversation this is Stenography.

Java compiler(javac) uses same technique to generate .class file. Java compiler converts one expression of our Source code into one symbol(Bytecode). The series of these symbols is the .class file.
Each symbol takes one byte of space on computer memory i.e. our one expression takes only one byte of space after conversion. That's why this code called Bytecode.

If you notice, Our Megabyte's source code file(.java) convert into of Kilobyte's(.class) after compilation. and It is just because of Bytecode.

Comments

Why "F" and "L" suffix | (10.0F, 10L)

Let us take it this way, We will create their needs. So we will get why they are needed. Try to guess, which functions will be executed in the following program: public class MyClass { public static void main(String args[]) { MyClass obj = new MyClass(); obj.fun1(10); } void fun1(byte val){ System.out.println(val); } void fun1(int val){ System.out.println(val); } void fun1(float val){ System.out.println(val); } void fun1(long val){ System.out.println(val); } } It seems like every method is capable to run this program because 10 is still literal because It has no data type. Before Java, In previous technologies, this scenario gave an ambiguity...

Promises and Async-await in depth : Asynchronous Programming in Javascript

Promises and Asynchronous Programming One of the most powerful aspects of JavaScript is how easily it handles asynchronous programming. As a language created for the Web, JavaScript needed to be able to respond to asynchronous user interactions such as clicks and key presses from the beginning. Node.js further popularized asynchronous programming in JavaScript by using callbacks as an alternative to events. As more and more programs started using asynchronous programming, events and callbacks were no longer powerful enough to support everything developers wanted to do. Promises are the solution to this problem. Promises are another option for asynchronous programming, and they work like futures and deferreds do in other languages. A promise specifies some code to be executed later (as with events and callbacks) and also explicitly indicates whether the code succeeded or failed at its job. You can chain promises together based on success or failure in ways that make your code...

Typecasting | How is Long to Float Conversion possible?

We will take a brief description of Typecasting and will try to do focus on Log to Float Conversion. Typecasting: Assigning a value of one data type to another. When we assign a value of smaller data type to a bigger one. it is called Widening. Java did this conversion automatically as they are compatible. As shown in the following figure: One another kind of conversion, when automatic conversion not possible i.e. when they are not compatible is Shortening. It will be just opposite of above and diagram will be reversed. How is Long to Float Conversion possible? If we look carefully at the diagram, there is one conversion which looks questionable is Long(8 bytes) to Float(4 bytes) conversion. It looks like data lossy conversion. Actually, Type conversion does two things: Either change in range or change in behavior or both. Change in Range: short a = 3456 // this value can be varied within the range of -32768 to 32767 int b = a // now this value can be varied wi...

Java Vines

Search This Blog