Christian Ullenboom - Java: The Comprehensive Guide to Java Programming for Professionals

[ ] The MESA programming language was developed in the 1970s at the Xerox Palo Alto Research Center (Xerox PARC). It was used to program the Xerox Alto , the first computer with a complete GUI. The syntax of MESA has similarities with Algol and Pascal.

[ ] Duke looks a bit like a tooth and therefore could for an ad for a dentist. The design is by Joe Palrang.

[ ] The idea of the bytecode is pretty old. The company Datapoint created the PL/B programming language around 1970, which maps programs to bytecode. Also, the original implementation of UCSD-Pascal, which was created around the beginning of 1980, uses an intermediate code ( p-code for short).

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[ ] This concept is also old: HP had JIT compilers for BASIC machines around 1970.

[ ] Dynamic method calls are usually extremely fast because the JVM knows the type hierarchy and can optimize aggressively. However, optimizations can be undone if the type hierarchy changes, for example, due to reloaded classes. The JVM also knows which program parts are executed concurrently and must be saved or whether synchronization can be omitted.

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[ ] However, this safety limitation is not entirely true. With reflection , you can access otherwise protected parts of memory if your security settings allow.

[ ] In C++, you could solve a variant with an overloaded operator.

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[ ] Actually, support should exist for USB, but in this caseand unfortunately elsewhere tooSun hasnt further pursued the project JSR-80 : Java USB API .

[ ] This option is known as Remote Method Invocation (RMI) . Certain objects can communicate with each other via the network.

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[ ] Not a single word about Java exists in Microsoft documents. Youll only read about the fact that C# had other languages, such as C++, VB, and Delphi, as models.

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[ ] Of course, Eclipse can also generate class files for Java 1.0; only the IDE itself requires at least Java 8.

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[ ] Whether a character is a letter is determined by the static Character.isLetter(...) method; whether its a valid identifier letter is indicated by the functions isJavaIdentifierStart(...) for the start letter and isJavaIdentifierPart(...) for the rest.

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[ ] Strictly speaking, as of Java 10.

[ ] Incidentally, in C++, developers have reintroduced the line comment character from the predecessor language BCPL, which had been removed from C.

[ ] However, not all the time. In a static block, you could also set a function call, but you shouldnt always assume you can. static blocks are executed when the classes are loaded into the virtual machine (VM). Other initializations are thus also already made.

[ ] The verb to implement derives from the Latin word implere , which means to fulfill and to supplement.

[ ] Note this shorthand for methods starting with print (i.e., print() and println() ).

[ ] The semicolon is also not used to separate statements, as in Pascal, but always terminates statements.

[ ] While in the literature agreement generally exists on the terms statically typed and dynamically typed , different authors have different ideas about the terms strictly (strongly) typed and weakly typed .

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[ ] In C(++) definition and declaration mean something different. In Java, no such difference exists, and we therefore consider both terms as equivalent. The specification only uses the term declarations .

[ ] In C, declarations like char (*(*a[2])())[2] are possible. Fortunately, the program cdecl is designed for reading out such definitions.

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[ ] In Java, long and short form their own data type. They dont serve as modifiers as in C(++). So, a declaration like long int i is just as wrong as long long time_ago .

[ ] For conversions between hours, minutes, etc., the TimeUnit class also helps with some static to*() methods.

[ ] A literal like makes it clear why identifiers cant do anything with a digit: If a variable declaration like double 1D = 2; were allowed, then the compiler wouldnt know whether stands for the literal or for the variable in println(1D) .

[ ] For understanding, check out the output of System.out.println( Float.toHexString( 20000000000F ) ); System.out.println( Float.toHexString( 20000000000F + 1F ) ); System.out.println( Double.toHexString( 20000000000D ) ); System.out.println( Double.toHexString( 20000000000D + 1D ) );

[ ] Some programming languages have built-in data types for currencies, such as LotusScript with Currency, which covers an exceptionally large and accurate range of values with 8 bytes. Surprisingly, once in C#, the currency data type could be used for integer currencies.

[ ] Some software, like Mathematica, warns about variables with almost identical names.

[ ] This behavior is different for object variables, static variables, and fields. By default, they are set to null (for references), (for numbers), or false .

[ ] Although the assignments look like mathematical equations, an important difference should be noted: The formula a = a + 1 cant be fulfilled mathematicallyat least not in the decimal system without additional algebrabecause no possible value of satisfies a = a + 1. From a programming point of view, however, this expression is OK and increases the value of the variable by one.

[ ] In some programming languages, value operations are specifically marked. For example, in LOGO, a value operation is written with a colon in front of the variable, as in :X + :Y .

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[ ] Mathematicians distinguish between the two terms remainder and modulo because a modulo is not negative, while the remainder in Java is. But this distinction is not important for our purposes.

[ ] Some methods dont start with lowercase letters, although this situation is rare and only occurs in special cases. For instance, ieeeRemainder() simply didnt look nice to the authors.

[ ] In the context of wrapper types, its use can be helpful because of the unboxing that takes place. More about on this topic later.

[ ] The abbreviation exists only in the program code, no compound assignment operator will exist in the bytecode.

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[ ] Yoda is a character from Star Wars who uses a word order in his sentences thats unusual for us. Instead of building sentences with subject + verb + object (SVO), Yoda uses the object + subject + verb (OSV); object and subject are reversed, as are the operands from the example, so this expression would read if 58000000000 equal to worldExpoShanghaiCostInUSD is instead of the usual SVO reading if worldExpoShanghaiCostInUSD is equal to 58000000000 . In Arabic, this OSV position is common, so developers from the Arabic-speaking world might actually find this form natural. If that's not worth a study ...

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[ ] Some (old) programming languages like APL dont follow any precedence rules. They evaluate expressions strictly from right to left, or vice versa.

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[ ] In the Python programming language, indentation determines affiliation.

[ ] The conditional operator is the only ternary operator in Java. In other programming languages there are more: Python, for example, allows array slicing with array[start : stop], where array, start, stop are three operands. Python goes even further and