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basic programming introduction about java
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- 2. What is aprogram? • The simplest definition is to view algorithm as a set of steps that define how a task is performed. • Computer programs, known as software, are instructions that tell a computer what to do. It is a representation of an algorithm is called a program. • The process of developing a program is known as “Programming”
- 3. What is aprograming language? • Computers do not understand human languages, so programs must be written in a language a computer can use. • A programming language is a special language used to write computer programs. • Categories of programming language: • Machine Language • Assembly Language • High-Level Language
- 4. MACHINE LANGUAGE • aset of built-in primitive instructions. These instructions are in the form of binary code. • The native language of the computer (understand directly) but are very difficult to read and modify.
- 5. ASSEMBLY LANGUAGE • Ituses a short descriptive word to represent each of the machine-language instructions. • Ex: add 2, 3, result • An instruction in assembly language essentially corresponds to an instruction in machine code. Writing in assembly requires that you know how the CPU works. • Because the computer cannot execute assembly language, another program—called an Assembler—is used to translate assembly- language programs into machine code.
- 6. HIGH-LEVEL LANGUAGE • Theyare platform independent, which means that you can write a program in a high-level language and run it in different types of machines. High-level languages are English-like and easy to learn and use like : Java • A program written in a high-level language is called a source program or source code. • a source program must be translated into machine code for execution. The translation can be done using another programming tool called an Interpreter or a Compiler. • An interpreter reads one statement from the source code, translates it to the machine code or virtual machine code, and then executes it right away. • A compiler translates the entire source code into a machine-code file, and the machine-code file is then executed
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- 9. Lifecycle of javaprogram • You save a Java program in a .java file and compile it into a .class file. The .class file is executed by the Java Virtual Machine( . Java source code is compiled into Java bytecode and Java bytecode is interpreted by the JVM.) • JVM(Java Virtual Machine): is a program that interprets Java bytecode. • one of Java’s primary advantages: Java bytecode can run on a variety of hardware platforms and operating systems.
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