ARRAYLIST in java

ArrayList implements all List operations using List interface and is also accept null values.The ArrayList is re sizable i.e shrinks and grows automatically and it has a capacity .

The class hierarchy is as follow:
---->Java.Lang.Object
      ----->Java.Util.AbstactCollection
                ----->Java.Util.AbstractList
                        ------>Java.Util.ArrayList

The array list contains following methods for implementing different operations

Return type	Method name
void	add (int index, Object o)
boolean	add (Object o)
boolean	addAll (Collection c)
boolean	addAll (int index,Collection c)
void	clear ( )
Object	clone ( )
boolean	contains (Object o )
Object	get (int index)
int	indexOf(Object o)
boolean	isEmpty( )
int	lastIndexOf( Object o)
Object	remove( int index)
Protected void	removeRange( int fromIndex, int toIndex)
Object	set (int index, Object o)
int	size ( )
Object [ ]	toArray( )
Object [ ]	toArray (Object [ ] a)
void	trimToSize( )

OPERATOR PRECEDENCE IN JAVA

Operators in Java are special symbols that executes specific operations on one, two, or three operand/operands, and then return a result.They moves to left to right or right to left.In the table bellow all the Java operators has been described with examples

ACCESS MODIFIER IN JAVA

There are 4 access modifier in core Java. They are public, private, protected and default.
The table bellow shows the access of class with different modifier

Access Modifier table

Visibility	PUBLIC	PROTECTED	DEFAULT	PRIVATE
Access from the same class	YES	YES	YES	YES
Acces from any class in same package	YES	YES	YES	NO
From subclass in same package	YES	YES	YES	NO
Access from subclass outside package	YES	YES through inheritance	NO	NO
Access from any non subclass outside package	YES	NO	NO	NO

JAVA KEYWORDS WITH EXPLANATION

There are near about 50 keywords ( reserved words) in core Java.The tables bellow demonstrate JAVA keywords with description and example and assigned alphabetically.Hope that you will find useful for learning or refreshing your memory......
Please inform me by posting comments if I am wrong...

keyword	description	example
Abstact	used in class and method declaration. Abstract class: 1) class must be declared with abstract keyword 2) methods in abstract class may or may not be abstract 3)If a class contains at-least one abstract method, the class must be declared as abstract. 4)Abstract methods must not be implemented in abstract class. Methods must be implemented in sub classes 5) An abstract class can not be instantiated, its solo mission is to be subclassed.	abstact class Myclass // abstract class { public abstact void do();// is a abstract method public String getName() { } }
Assert	followed by a boolean value (true or false), or an expression,  to be evaluated at runtime, that returns a  boolean value. If the boolean expression evaluates to false, then an AssertionError is thrown.	assert true; assert 50 == 50; // this will throw an Assertion Error: int test = 50; assert test == 100;
boolean	is a data type which stores boolean value, i.e True or False. It is also used to declare methods that returns a value which is also a boolean.	boolean myFlag = true;
break	One of the control statement to control the program flow. used to break the loop of switch statement. 1) Unlabeled Break statement 2) Labeled Break Statement	1) Unlabeled Break statement for(int num =0; num < 5 ; var++) {      System.out.println(“Num is : “ + num);   if(num == 3)      break; } 2)Labeled Break Statement Back: for(int num1=0; var1 < 10 ; num1++) {  for(int num2 = 1; num2 < 10; num2++)  {             System.out.println(“num1:” + num1 + “, num2:” + num2);      if(num1 == 5) break Back;  } }
byte	8 bit signed 2's complement integer	byte b = -1;
case	case is used in Switch statement	switch ( value/variable to test ) { case value:     your code_here; break; case value: your code_here; break; default: value/variable_not_above; }
catch	use with try block to catching exceptiion	try { code here} catch( exception ) {}
char	character type in unicode	char test ="y"
class	implementation of a particular kind of object which defines instance, class fields, methods,innner classes,interfaces as well as  superclasses of class	class Person { private String name; public Person(String myName) { this.name = myName; } public void show() { System.out.println(name); } } classs Strudent extends Person { Pesron p = new Person(); p.show(); }
const	is keyword in Java, but till now not used
continue	to skip the rest of the statement in body of the loop and continue with the next iteration of the loop 1)Unlabeled Continue 2)labeled Continue	1)Unlabeled Continue  for(int num1 =0; num1 < 15 ; num1++) {    for(int num2=0 ; num2 <1 5 ; num2++)  {      if(num2 == 2)            continue;   System.out.println( num1 + num2);  } } 2) Labeled Continue Back: for(int num1 =0; num1 < 5 ; num1++) {  for(int num2=0 ; num2 < 5 ; num2++)   {        if(var2 == 2)         continue Back;  System.out.println( num1 + num2);    } }
default	can optionally be used in "Switch case"  labelling a block of statement which is to be executed	see case
do	use with while to form "do-while" loop uses boolean  expression to execute block of statements	do {      statement(s) } while (expression);
double	64-bit double precision IEEE 754  floating-point number	double mydouble = 0.05;
else	use with "if " to form "if else" or "else if" statement tests boolean expression	int score = 79;         char status;         if (score >= 90) {             status= 'A';         } else if (score >= 80) {             status = 'B';         } else if (score >= 70) {             status = 'C';         } else if (score >= 60) {             status = 'D';         } else {             status = 'F';         }         System.out.println("status = " + grade);
enum	enumeration is a type whose  field consist of a fixed value of constant. It extends base class called Enum	public enum Day {  SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY }