DAY 2

DAY-2
JAVA
COMMAND LINE ARGUMENT
The command line argument is the argument passed to a program at the time when you run it. To access the command-line argument inside a java program is quite easy, they are stored as string in String array passed to the args parameter of main() method.
class a
{
public static void main(String s[])
{
System.out.println(s[0]);
System.out.println(s[1]);
}
}
In above example, input is given by users in command prompt like:
javac a.java
java a 10 20
To perform operation we have to convert the String data type into Integer
class a
{
public static void main(String s[])
{
System.out.println(s[0]);
System.out.println(s[1]);
int x=Integer.parseInt(s[0]);
int y=Integer.parseInt(s[1]);
System.out.println(x+y);
}
}

OPERATORS
Java provides a rich set of operators to manipulate variables. We can divide all the Java operators into the following groups −
  • Arithmetic Operators
  • Relational Operators
  • Bitwise Operators
  • Logical Operators
  • Assignment Operators
  • Misc Operators

The Arithmetic Operators

Arithmetic operators are used in mathematical expressions in the same way that they are used in algebra.
OperatorDescriptionExample
+ (Addition)Adds values on either side of the operator.A + B will give 30
- (Subtraction)Subtracts right-hand operand from left-hand operand.A - B will give -10
* (Multiplication)Multiplies values on either side of the operator.A * B will give 200
/ (Division)Divides left-hand operand by right-hand operand.B / A will give 2
% (Modulus)Divides left-hand operand by right-hand operand and returns remainder.B % A will give 0
++ (Increment)Increases the value of operand by 1.B++ gives 21
-- (Decrement)Decreases the value of operand by 1.B-- gives 19

The Relational Operators

There are following relational operators supported by Java language.
OperatorDescriptionExample
== (equal to)Checks if the values of two operands are equal or not, if yes then condition becomes true.(A == B) is not true.
!= (not equal to)Checks if the values of two operands are equal or not, if values are not equal then condition becomes true.(A != B) is true.
> (greater than)Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true.(A > B) is not true.
< (less than)Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true.(A < B) is true.
>= (greater than or equal to)Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true.(A >= B) is not true.
<= (less than or equal to)Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true.(A <= B) is true.

The Bitwise Operators

Java defines several bitwise operators, which can be applied to the integer types, long, int, short, char, and byte.
OperatorDescriptionExample
& (bitwise and)Binary AND Operator copies a bit to the result if it exists in both operands.(A & B) will give 12 which is 0000 1100
| (bitwise or)Binary OR Operator copies a bit if it exists in either operand.(A | B) will give 61 which is 0011 1101
^ (bitwise XOR)Binary XOR Operator copies the bit if it is set in one operand but not both.(A ^ B) will give 49 which is 0011 0001
~ (bitwise compliment)Binary Ones Complement Operator is unary and has the effect of 'flipping' bits.(~A ) will give -61 which is 1100 0011 in 2's complement form due to a signed binary number.
<< (left shift)Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand.A << 2 will give 240 which is 1111 0000
>> (right shift)Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand.A >> 2 will give 15 which is 1111
>>> (zero fill right shift)Shift right zero fill operator. The left operands value is moved right by the number of bits specified by the right operand and shifted values are filled up with zeros.A >>>2 will give 15 which is 0000 1111

The Logical Operators

OperatorDescriptionExample
&& (logical and)Called Logical AND operator. If both the operands are non-zero, then the condition becomes true.(A && B) is false
|| (logical or)Called Logical OR Operator. If any of the two operands are non-zero, then the condition becomes true.(A || B) is true
! (logical not)Called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOT operator will make false.!(A && B) is true

The Assignment Operators

OperatorDescriptionExample
=Simple assignment operator. Assigns values from right side operands to left side operand.C = A + B will assign value of A + B into C
+=Add AND assignment operator. It adds right operand to the left operand and assign the result to left operand.C += A is equivalent to C = C + A
-=Subtract AND assignment operator. It subtracts right operand from the left operand and assign the result to left operand.C -= A is equivalent to C = C – A
*=Multiply AND assignment operator. It multiplies right operand with the left operand and assign the result to left operand.C *= A is equivalent to C = C * A
/=Divide AND assignment operator. It divides left operand with the right operand and assign the result to left operand.C /= A is equivalent to C = C / A
%=Modulus AND assignment operator. It takes modulus using two operands and assign the result to left operand.C %= A is equivalent to C = C % A
<<=Left shift AND assignment operator.C <<= 2 is same as C = C << 2
>>=Right shift AND assignment operator.C >>= 2 is same as C = C >> 2
&=Bitwise AND assignment operator.C &= 2 is same as C = C & 2
^=bitwise exclusive OR and assignment operator.C ^= 2 is same as C = C ^ 2
|=bitwise inclusive OR and assignment operator.C |= 2 is same as C = C | 2

Miscellaneous Operators

There are few other operators supported by Java Language.

Conditional Operator ( ? : )

Conditional operator is also known as the ternary operator. This operator consists of three operands and is used to evaluate Boolean expressions. The goal of the operator is to decide, which value should be assigned to the variable.
(condition)? (true_value):(false_value)
class a
{
public static void main(String s[])
{ int i=2;
int j=(i>1)?30:40
}
}
output: 30

CONTROL STATEMENTS:
A control statement is a statement that determines whether other statements will be executed. An if statement decides whether to execute another statement, or decides which of two statements to execute. A loop decides how many times to execute another statement. Types of control statements:
1. Selection Statement.
2. Iteration Statement.
3. Jump Statement.

SELECTION STATEMENT

1. IF-ELSE statement
  • if statement is a conditional branch statement. This is a two way branch statement. Depending upon the whether a condition is true or false, the corresponding code is executed.
  • if(condition)
  • {
  • ......
  • }
  • else
  • {
  • .....
  • }
2. IF-ELSE IF statement
       if(condition)
       {
        .......
       }
       else if(condition)
       {
       .......
        }
        else
        {
        ......
        }

3. NESTED statement
      if(condition)
      {  if (condition)
         {
       .....
          }
       }

ITERATION STATEMENT

1. FOR LOOP statement
for(initialization;condition;incr/decr)
{  
//code to be executed  
} 

2.WHILE statement
The most fundamental loop statement of Java is the while loop. The while loop executes a statement over and over again until the controlling expression evaluates to true. The general form of while loop is:
while(condition)
{
....
}
3. DO-WHILE statement
The do-while statement will execute the body atleast once as the conditional expression is placed at the bottom of the loop.
The general form of do-while loop is
do
{
......
}
while(condition);

JUMP STATEMENT 

Jump Statements in Java Example. Java supports three jump statements: break, continue, and return. These statements transfer control to another part of the program. The break construct is used to break out of the middle of loops: for, do, or while loop.
class NumberExcept
{
            public static void main(String args[] )
            {
                        int i;
                        for(i=1;i<=10;i++)
                        {
                                    if(i==5) continue;
                                    System.out.print(i +" ");
                        }
            }
}
OUTPUT: 1 2 3 4  6 7 8 9 10

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