Array concept in java pdf

Disclosure: Hackr. When you purchase through links on our site, we may earn an affiliate commission. Open Source: Readily available for development. Platform-neutral: Java code is independent of any particular hardware or software. This is because Java code is compiled by the compiler and converted into byte code.

Thus, byte code is platform-independent and can run on multiple systems. The only requirement is Java needs a runtime environment, i. Memory Management: Garbage collected language, i.

Exception Handling: Catches a series of errors or abnormality, thus eliminating any risk of crashing the system. Java was modeled in its final form, keeping into consideration the primary objective of having the following features. Read here: Major features of Java programming. It is a method of converting a variable of one data type to another data type to process these variables correctly. Java code can also be written in any text editor and compiled on the terminal with the following commands :.

Note : Filename should be the same as the class name containing the main method, with a. Variables are the name of the memory location. It is a container that holds the value while the java program is executed. Variables are of three types in Java :. Also known as keywords, particular words are predefined in Java and cannot be used as variable or object names.

Some of the important keywords are :. Where type - the return type of the method name - The name of the method parameter list - sequence of type and variables separated by a comma return - statement to return value to calling routine.

Test the condition; if a particular case is true, the control is passed to that block and executed. The rest of the cases are not considered further, and the program breaks out of the loop. Loops are used to iterate the code a specific number of times until the specified condition is true. There are three kinds of the loop in Java :. An object-oriented paradigm offers the following concepts to simplify software development and maintenance.

Objects are basic runtime entities in an object-oriented system, which contain data and code to manipulate data. This entire set of data and code can be made into user-defined data types using class concepts. Hence, a class is a collection of objects of a similar data type. The wrapping or enclosing up of data and methods into a single unit is known as encapsulation.

This insulation of data from direct access by the program is called data hiding. For instance, while using apps, people are concerned about their functionality and not their code. Inheritance provides the concept of reusability; it is how objects of one class Child class or Subclass inherit or derive properties of objects of another class Parent class.

Defined as the ability to take more than one form. Polymorphism allows creating clean and readable code. In Java Polymorphism, the concept of method overloading and method overriding is achieved, which is the dynamic approach.

In a class hierarchy, when a method in a child class has the same name and type signature as a method in its parent class, then the method in the child class is said to override the method in the parent class.

Java programming can have two or more methods in the same class sharing the same name, as long as their arguments declarations are different. Such methods are referred to as overloaded, and the process is called method overloading. Superclass only defines a generalized form shared by all of its subclasses, leaving it to each subclass to implement its methods. Thus, they are similar to class except that they lack instance variables, and their methods are declared without anybody.

Learn more about Java Constructor. Package Access Modifiers Encapsulation. Exception in thread "main" java. Printing original array: 33 3 4 5 Printing clone of the array: 33 3 4 5 Are both equal? Next Topic Wrapper classes in Java. Reinforcement Learning. R Programming. React Native. Python Design Patterns. Python Pillow.

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Operating System. Computer Network. Compiler Design. Computer Organization. Instance variables 2. Static variables 3. For every object a separate copy of instance variables will be created.

Instance variables will be created at the time of object creation and destroyed at the time of object destruction hence the scope of instance variables is exactly same as scope of objects. Instance variables will be stored on the heap as the part of object. Instance variables should be declared with in the class directly but outside of any method or block or constructor. Instance variables can be accessed directly from Instance area.

But cannot be accessed directly from static area. But by using object reference we can access instance variables from static area. We have to declare such type of variables at class level by using static modifier.

In the case of instance variables for every object a separate copy will be created but in the case of static variables for entire class only one copy will be created and shared by every object of that class. Static variables will be crated at the time of class loading and destroyed at the time of class unloading hence the scope of the static variable is exactly same as the scope of the.

Static variables will be stored in method area. Static variables should be declared with in the class directly but outside of any method or block or constructor. Static variables can be accessed from both instance and static areas directly. We can access static variables either by class name or by object reference but usage of class name is recommended. But within the same class it is not required to use class name we can access directly. Start JVM. Locate find Test. Load Test.

Unload Test. Shutdown JVM. Local variables: Some times to meet temporary requirements of the programmer we can declare variables inside a method or block or constructors such type of variables are called local variables or automatic variables or temporary variables or stack variables. Local variables will be stored inside stack. The local variables will be created as part of the block execution in which it is declared and destroyed once that block execution completes.

Hence the scope of the local variables is exactly same as scope of the block in which we declared. For the local variables JVM won't provide any default values compulsory we should perform initialization explicitly before using that variable. It is highly recommended to perform initialization for the local variables at the time of declaration at least with default values. Note: The only applicable modifier for local variables is final.

If we are using any other modifier we will get compile time error. For the static and instance variables it is not required to perform initialization explicitly JVM will provide default values.

For every object a separate copy of instance variable will be created whereas for entire class a single copy of static variable will be created. For every Thread a separate copy of local variable will be created. Instance and static variables can be accessed by multiple Threads simultaneously and hence these are not Thread safe but local variables can be accessed by only one Thread at a time and hence local variables are Thread safe. If we are not declaring any modifier explicitly then it means default modifier but this rule is applicable only for static and instance variables but not local variable.

E: variable a might not have been initialized System. Every variable in java should be either instance or static or local. Every variable in java should be either primitive or reference Hence the following are the various possible combinations for variables Var- arg methods variable no of argument methods 1. Of arguments. If there is a change in no of arguments compulsory we have to define a new method.

This approach increases length of the code and reduces readability. But from 1. Of arguments such type of methods are called var-arg methods. We can call or invoke this method by passing any no. Of int values including zero number also. Example: methodOne int a,int Example: methodOne int Case 6: For the var-arg methods we can provide the corresponding type array as argument. Cannot declare both methodOne int Note : 1.

Even though above syntax is very strict but the following changes are acceptable to main method. The order of modifiers is not important that is instead of public static we can take static public.

We can declare string[] in any acceptable form o String[] args o String []args o String args[] 3. Instead of args we can use any valid java identifier. We can replace string[] with var-arg parameter. Example: main String No case, in all the cases we will get runtime exception. Case 1 : Overloading of the main method is possible but JVM always calls string[] argument main method only.

Case 2: Inheritance concept is applicable for static methods including main method hence while executing child class if the child class doesn't contain main method then the parent class main method will be executed.

The main objective of command line arguments are we can customize the behavior of the main method. Whenever we are writing any component i. Should starts with uppercase letter and if it contains multiple words every inner word should starts with upper case letter.

Should starts with upper case letter and if it contains multiple words every inner word should starts with upper case letter. Serializable 2. Runnable 3.