Java syntax

Some features like operator overloading or unsigned integer data types are omitted to simplify the language and avoid possible programming mistakes.

The Java syntax has been gradually extended in the course of numerous major JDK releases, and now supports abilities such as generic programming and anonymous functions (function literals, called lambda expressions in Java).

They are declared by writing the variable's type and name, and are optionally initialized in the same statement by assigning a value.

Multiple variables of the same type can be declared and initialized in one statement using comma as a delimiter.

Class members and the body of a method are examples of what can live inside these braces in various contexts.

Classes in the package java.lang are implicitly imported into every program, as long as no explicitly-imported types have the same names.

It is possible to omit it causing the execution to proceed to the next label, however, a warning will usually be reported during compilation.

Since Java 14 it has become possible to use switch expressions, which use the new arrow syntax: Alternatively, there is a possibility to express the same with the yield statement, although it is recommended to prefer the arrow syntax because it avoids the problem of accidental fall throughs.

It is possible to include several expressions of the same kind using comma as delimiter (except in the condition).

Unlike C#, this kind of loop does not involve a special keyword, but instead uses a different notation style.

The exception is propagated upwards through the call stack until a matching catch block is found within one of the currently active methods.

In a try-with-resources statement the try keyword is followed by initialization of one or more resources that are released automatically when the try block execution is finished.

These types of statements are used to make assertions in the source code, which can be turned on and off during execution for specific classes or packages.

This statement can include a colon followed by another expression, which will act as the exception's detail message.

When the constructor is called, an object is created on the heap and a reference is assigned to the variable.

As doing this can confer security and efficiency benefits, many of the Java standard library classes are final, such as java.lang.System and java.lang.String.

Instance initializers are declared in a block without any keywords: Since Java has a garbage collection mechanism, there are no destructors.

A method has a return value, a name and usually some parameters initialized when it is called with some arguments.

[5] This is used to prevent unexpected behavior from a subclass altering a method that may be crucial to the function or consistency of the class.

Only the runtime environment and JIT compiler know exactly which classes have been loaded, and so only they are able to make decisions about when to inline, whether or not the method is final.

For example: Unlike C++, all non-final methods in Java are virtual and can be overridden by the inheriting classes.

A class C has abstract methods if any of the following is true: Output: This language feature was introduced in J2SE 5.0.

Interface methods are allowed to have a subset of access modifiers depending on the language version, strictfp, which has the same effect as for classes, and also static since Java SE 8.

Lambda's parameters types don't have to be fully specified and can be inferred from the interface it implements.

However, it is possible that several interfaces have a field with the same name, in which case it becomes a single ambiguous member, which cannot be accessed.

An interface can have a method with a body marked as private, in which case it will not be visible to inheriting classes.

Also they may have a default value, which is declared using the default keyword after the method name: Annotations may be used in any kind of declaration, whether it is package, class (including enums), interface (including annotations), field, method, parameter, constructor, or local variable.

The main purpose of generics is to ensure type safety and to detect runtime errors during compilation.

In this case the type variable is appended by the extends keyword followed by a name of the class or the interface.

Since Java SE 7, it is possible to use a diamond (<>) in place of type arguments, in which case the latter will be inferred.