Java syntax: Difference between revisions

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===={{mono|java.lang.String}}====

{{code|java.lang.String}} is Java's basic string type. It is [[immutable object|Immutableimmutable]]. It does not implement {{code|Iterable<Character>}}, so it cannot be iterated over in a for-each loop, but can be converted to <code>char[]</code>. Some methods treat each [[UTF-16]] code unit as a <code>char</code>, but methods to convert to an <code>int[]</code> that is effectively [[UTF-32]] are also available. <code>String</code> implements <code>CharSequence</code>, so <code>char</code>s in the <code>String</code> can be accessed by the method <code>charAt()</code>.

===={{mono|java.lang.Throwable}}====

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==Operators==

Operators in Java are similar to those in [[C++]]. However, there is no <code>delete</code> operator due to [[Garbage collection (computer science)|garbage collection]] mechanisms in Java, and there are no operations on [[Pointer (computer programming)|pointers]] since Java does not support them. Another difference is that Java has an unsigned right shift operator (<code>>>></code>), while C's right shift operator's signedness is type-dependent. Operators in Java cannot be [[Operator overloading|overloaded]]. The only overloaded operator is <code>operator+</code> for string concatenation.

{| class="wikitable"

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===Iteration statements===

Iteration statements are statements that are repeatedly executed when a given condition is evaluated as true. Since [[J2SE 5.0]], Java has four forms of such statements. The condition must have type <code>boolean</code> or Boolean, meaning C's<syntaxhighlight code>java.lang="c".Boolean</code>.

For example, the following code is valid in C but results in a compilation error in Java.

<syntaxhighlight lang="c">

while (1) {

doSomething();

}

</syntaxhighlight>results in a compilation error.

====<code>while</code> loop====

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</syntaxhighlight>

Like C, all three expressions are optional. The following loop isnever infiniteterminates:

<syntaxhighlight lang="java">

for (;;) {

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</syntaxhighlight>

====Enhanced <code>for</code>Foreach loop====

{{Main|Enhanced forForeach loop}}

[[enhanced for loop|Enhanced <code>for</code>Foreach loop]]s have been available since [[J2SE 5.0]]. This type of loop uses built-in iterators over arrays and collections to return each item in the given collection. Every element is returned and reachable in the context of the code block. When the block is executed, the next item is returned until there are no items remaining. This for loop from Java was later added to [[C++11]]. Unlike [[C Sharp (programming language)|C#]], this kind of loop does not involve a special keyword, but instead uses a different notation style.

<syntaxhighlight lang="java">

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Due to the nature of the multi-dimensional arrays, sub-arrays can vary in length, so multi-dimensional arrays are not bound to be rectangular unlike C:

<syntaxhighlight lang=Java>

int[][] numbers = new int[2][]; // Initialization of the first dimension only

numbers[0] = new int[3];

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String str;

Foo() { // Constructor with no arguments

Foo() {}

// Initialization

}

Foo(String str) { // Constructor with one argument

Foo(String str) {

this.str = str;

}