java class1
TRANSCRIPT
JAVA DAY 1 TRANING
--ByPRUDHVI AKELLA
Source code(.java) Javac(java compiler) .class file(intermediate code or byte
code)
JVM(java virtual
machine)
JVM is different for each OS(Linux, windows)Where jvm will convert any byte code into machine code. that's why java is called as
platform independent.
Machine codeProcessor
Memory Management
Processor
Processor will create memory for JVM
JVM
1).Jvm will use that part of
limited memory to create
objects, which is created by
Processor
2).So as the memory is limited and filled soon.so when object is no
longer used by program memory will be destroyed
by a Garbage Collector (GC) it is
special Thread.
3) Memory where JVM creates an
object called HeapGC Thread is also
called as Demon Thread.
What function can call Garbage collector?
Runtime.gc();
How Memory will be Destroyed By GC?
object
reference
HEAP
object
reference
HEAP
Cloud Represents The HEAP Memory created by processor for JVMFigure1 show the link between the reference and object
Figure2 shows link got destroyed between reference and object.When There is no link between Object and reference The GC will destroy the memory for
reference and object(shown in figure3)
object
reference
HEAP
How java works?
• When java source code is converted as .class(byte code) file by compiler.• The byte code moves through network or local host.
• The class loader loads the byte code into JVM.• The byte code verifier contains some predefined format . if the byte code is not in that
format it throws and error.• The interpreter interprets the Byte code into machine(it will execute line by line).the main
use of just in time compiler is if interpreter find repeated code(for example 10) it will pass those lines of code to complier it will execute and store it in cache memory when
interpreter again encounters the redundant code then I will directly fetch instructions from cache(fastest memory and temporary memory). This way process will become faster
Interpreter
JIT(just in time compiler)
Cache memory
Code lines
Green lines are the normal code lines.
Orange lines are the repeated code lines.
Path 1 is when interpreter find t he repeated code for first
time.Path 2 is when interpreter find
the code for second time.
1 1
12
2
1
2
Date Types in java(data types defines the nature of the value).
Primitive types and variables and naming convention(java is not a purely object oriented programing due to primitive data types in java).
Statement and Blocks.
Flow of Control.
IF_ELSE syntax
NESTED if_else syntax
Switch case syntax
Operators
Assignment and Athematic Operator
Relational Operator
Logical Operator
Logical Operator
Static Variables VS dynamic Varibles
Static Variables Example
package pratice;
public class Pratice {
static int preatice = 12;
public static void main(String[] args) {
classs1s obj = new classs1s();obj.fun();
}}
public class classs1s {void fun(){
System.out.println(Pratice.preatice);Pratice.preatice = 20;System.out.println(Pratice.preatice);
} }