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Java, language differences (non-syntax) compilation, execution, file…

- - - - what makes java portable and archtecture neutral?
        
        Hybrid language
        
        step 1. source code(.java) compiled into object(.class, bytecode)
        step 2. JVM interprets the object(byte)code
        
        2 advantages
        
        programs can run on any cpu as long as JVM is installed
        interpretation in JVM takes less time since it is interpreting low-level(object/byte) code, not high-level like purely interpreted langs(python)
    - - example
        
        a c++ programmer can pick up java with little training needed
    - - this has been mproved in java due to the recent introduction of
        
        in the case of loops, the statment within a loop must be interpreted each time around the loop
        
        execution times are especially long
        
        code executed immediately after editing, no compilation step in between
        execution time is increased since each line must be interpreted each time the program is executed
        
        1 advantage
        1 disadvantage
        
        Interpreted language
        
        2 more items...
        
        Just-in-time compilation
        
        reduces execution time in cases where methods are executed frequently(functions/blocks of code are called frequently like in a loop)
        
        reduces JVM overhead
        
        overhead
        
        increased computation time/resources(ex:memory or bandwidth)
        
        converts bytecode to native machine code at runtime
        
        removing the need for the JVM to interpret it
      - helps ensure memory is available
    - - what makes java robust?
        
        automatic garbage collection
        
        garbage
        
        memory allocated on the heap that is no longer reachable by pointer
        
        example
        
        linkedList* someList = new LinkedList();
        someList = nullptr;
      - capacity of a computer system to handle the errors during execution and manage the incorrect input of data
- - - - JAR
        
        7 benefits of Jar files
        
        SDCPPPP
        
        packaged for sealing
        
        Compressed
        
        Decreased Download Time
        
        leading to
        
        because it is
        
        packaged for extension
        
        allows your software to become extensions of the java platform
        
        portable
        
        Java core api provides handling for jar files
        any platform with java on it can handle jars
        
        packaged for versioning
        
        jars contain version and vendor info
        
        jar feature that allows the package to enforce version consistency
        
        1 more item...
        
        as well as time of creation
        
        1 more item...
        
        Secure
        
        Jar files can be digitally signed by their author
        
        users of the software who recognize the signature can choose to grant it permissions
        
        a single archive containing all the class files and auxilary resourcess needed for certain applets/applications
        
        due to this bundling, only one HTTP transaction is needed, instead of one per file
        
        is a variety of zip file
        
        zip files
        
        good for 4 things
        
        compression
        
        advantages/disadvantages
        
        1 more item...
        
        decompression
        
        archiving
        
        unarchiving
        
        meaning this command will work
        
        unzip -l allInOne.jar
        
        Java Archiver/Java archive tool, java archive file
      - JVM
        
        Java virtual machine
        
        an instance of this is created when the java launcher tool is ran
- - - - typical platforms
        
        hardware or software in which a program runs, often described as a cross between the operating system and underlying hardware
        
        Platform
  - - - java API
        
        provides wide array of classes for us to use in our code
        
        User interface toolkits to build GUIs
        
        JavaFX
        
        Java 2D
        
        Swing
        
        application programming interface
- - - - implementation(.cpp)
- - - - module(.py)
- - - - c++
        
        java
        
        python
        
        boolean
        
        3 kinds of primitives in c++
        
        integer numbers
        
        int
        
        long int
        
        unsigned int
        
        unsigned long
        
        char
        
        floating point numbers
        
        float
        
        double
        
        logical values
        
        bool
    - - 3 kinds of type builders
        
        arrays
        
        structured types
        
        address types
    - - classes