code into a special representation called byte code Java byte code is not the

Code into a special representation called byte code

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code into a special representation called byte-code § Java byte-code is not the machine language of any computer - it is platform independent § As in the previous approach, a linking step ( class loader ) is involved, in which other pieces of code (usually compiled) are fetched from elsewhere (in current or the another directory or even across a network from another machine) and put together with the current program to make code which can be run immediately Java Translation and Execution
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18 § An interpreter(another program) translates each byte-code instruction into machine language and executes it §This interpreter is called Java Virtual Machine(JVM) – a part of the JDK and the foundation of the Java platform §If the same JVM is available on many platforms, applications that it executes can be used on all those platforms Java Translation and Execution
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19 § Thus the Java compiler is not tied to any particular computer §Java is considered to be architecture neutral Java Translation and Execution
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20 § FORTRAN and COBOL were the first important high-level languages (developed in the 1950s and 1960s for mathematical computation and business data processing respectively) § BASIC and Pascal followed for microcomputers and academic uses respectively § A really powerful general purpose high level programming language called C was developed by the AT&T Bell Labs in the early 1970s History of Java and Object-Oriented Programming
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21 § In the 1980s people started to realise that the Object-Oriented (OO) style of programming would help manage the complexity of software § Simula (1960s) was the first OO language § It was followed by Smalltalk § In the early 1980s Bjarne Stroustrup (at Bell Labs) developed C++ as an extension of C to eliminate C’s weaknesses and enable Object- Oriented Programming (OOP) History of Java and Object-Oriented Programming
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22 § In the 1990s people wanted even more complex (and bigger) software and the World-Wide Web (WWW) and OOP were becoming very popular § And then along came Java § A new free object-oriented general purpose programming language designed to be used easily with Internet-based applications § Java was developed at Sun Microsystems (now part of Oracle) – it was based on C and C++ History of Java and Object-Oriented Programming
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23 § The earliest versions date from 1995 (called JDK 1.0, 1.1). JDK 1.2 was released in 1998 § Java 2 Platform (Java 2 SDK version1.4) was released in 2003 and Java 2 Platform Standard Edition version 5.0 (J2SE 5.0, also called jdk1.5) was released at the end of September 2004 § Java 2 Platform Standard Edition version 6.0 (Java 6, also called jdk1.6) was released in December 2006 § A number of updates of Java 6 were released until June 2011 History of Java and Object-Oriented Programming
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24 § Java 2 Platform Standard Edition version 7.0 (Java SE 7), which was a major update to Java, was released on 28 July 2011 § Today we use Java 2 Platform Standard Edition version 8.0 (Java SE 8), which was released on 18 March 2014 – available for download at: § javase/downloads/index.html History of Java and Object-Oriented Programming
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