Java Virtual Machine (JVM)

All language compliers translate source code into machine code for a specific computer. Java complier also do the same things but Java compiler produce an intermediate code known as bytecode. This machine is called as Java Virtual Machine(JVM) and it is exists only inside the computer memory with java. It is simulated computer within computer and does all major functions of real computer.

The virtual machine code is not machine specific. The machine specific code is generated by the Java Interpreter by acting as an intermediary between the virtual machine and the real machine. The interpreter is different for different machine.

The java object framework acts as the intermediary between the user program and virtual machine which turns act as the intermediary between operatinf system and the java object framework.

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Access Modifiers in Java

Introduction There are two types of modifiers in Java: access modifiers and non-access modifiers. The access modifiers in Java specifies the accessibility or scope of a field, method, constructor, or class. We can change the access level of fields, constructors, methods, and class by applying the access modifier on it. There are four types of Java access modifiers: 1. Private: The access level of a private modifier is only within the class. It cannot be accessed from outside the class. 2. Default: The access level of a default modifier is only within the package. It cannot be accessed from outside the package. If you do not specify any access level, it will be the default. 3. Protected: The access level of a protected modifier is within the package and outside the package through child class. If you do not make the child class, it cannot be accessed from outside the package. 4. Public: The access level of a public modifier is everywhere. It can be accessed from within the clas...

Decision Making and Branching Statements / Control Statements

Introduction Java is a set of statements which executed sequentially in the order in which they appear. This will happen when option or repetitions of certains are not necessary. However, We have a number of situation, where we may have to change the order of execution of statement on bases of certain conditions. This involves a kind of dicision making to see the particular condition occured or not and the direction of execution will execute according to it. When program braks the sequential flow and jump on the another part of code then it's called branching . When branching is on particular condition then it's called conditional branching . If branches executes without any particular conditions then it's call unconditional branching . Java supports such decision making capabilities and supports following statements known as Control statement or Decision making statement . if statements switch statement ...

Static and this keyword

Static Keyword: Most of the time static keyword in java use for memory management. We can use static keyword with variables, methods and also with block (Static block) . 1. Static with variables: If we declare static keyword with variables then it's called static variables . Static variables are use to access or refer common properties of all objects. The static varibels gets memory only once at the time of loading class loading. It makes program more efficient i.e., It saves memory. For example, static int length=100; 2. Static with method: If we use static keyword with method then it's called static method . The static method is belong to class rather than object of class. Static method can invoke or call without creating instance or object of class. For example, static void print(){ System.out.println("Welcome in Java"); } Examples of static variable, method an...

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