Transcript LAB SESSION-5

LAB SESSION-5
Topics covered
User input using keyboard. java
User input using JoptionPane
Arithmetic expression…………….
Math class……………………………
Testing………………………………….
Eg of keyboard. java
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{
}
Public class key
Public static void main(String args)
{
String name;
System.out.println(“Enter name:”);
name = KeyBoard.readString();
System.out.println(“My name is: “+name);
}
Input:
Enter name: Anand
Output: My name is:Anand
JOPTION PANE
Eg program
import javax.swing.*;
Public class AsampleGuiProgram
{
Public static void main(String args[])
{
String name;
String temp;
Int age;
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name= JOptionPane.showInputDialog(“Enter name”);
Temp= JOptionPane.showInputDialog(“Enter age”);
Age= Integer.Parseint (temp);
JOptionPane.showMessageDialog (“The age of” + name + ”is” +age););
System.exit(0);
}
i/p: Enter name:anand Enter age:23
o/p : The age of anand is 23
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Two methods in JOptionPane class
JOptionPane.ShowInputDialog(“xxxx”);
JOptionPane.ShowMessageDialog(“xxxx”);
The first method displays a window to get
an input
The second method displays a window to
display an output
Arithmetic expression
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An expression is a combination of one or more operators
and operands
the basic arithmetic operations defined for integer type
and floating point type are
addition(+),subtraction(-,multiplication(*),division(/).
Java has one more arithmetic operation remainder(%)
17%4 will return 1
a= b + c;
a,b,c – operands
+ -operator
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Result=14+8/2;
ans=18
ans=11
correct ans is 18
operator precedence hierarchy
division/multiplication/%
add/sub /concatenation
assignment
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Result=(14+8)/2;
ans=11;
result=((18-4)*(2+2));
=(14*4)
= 56
expression should be syntactically correct
no of left parenthesis should be =no of right parenthesis
Result=((19+6)%3)*3); //invalid
Result=2+8-6;
usually u start from left when same level of precedence
Testing
What to u mean by testing……..
 After your code has been written and the program is
ready to be run…
 U have to give different inputs in order to test that the
program runs for all conditions…
 If u’r program runs only for certain inputs
then it is said to be inefficient
Eg if u are asked to enter a input between 1 cent to 100
cents
Give i/p - 0 cents,100cents,(boundary cases)
any i/p in the middle 30cents,44cents etc
or any exceptional cases
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MATH CLASS
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The math class provides a large no of
basic mathematical functions.
Math class is defined in java.lang package
It has a lot of methods
absolute, acos, asin, atan,cos,tan,sin
Exp,random,sqrt,pow
Sqrt method
Syntax
static double sqrt(double num)
Eg
Public static void main (string args[])
{
Double no=5.00;
Double square=0;
Square= Math.sqrt(no);
System.out.println (“The square of no is: “ + Square);
}
Output:The square of no is: 25
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Power method
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Syntax
static double pow(double x,double y)
Eg
Public static void main (string args[])
{
Double x=2;
Double y=3;
Double power;
power= Math.pow(x,y);
System.out.println (“The value of power is: “ + power);
}
Output:The value of power is:8
Exponent
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Syntax
static double exp (double power)
Eg
Public static void main (string args[])
{
Double power=2;
power= Math.exp(power);
System.out.println (“The value is: “ + power);
}
 The value is:ex
Random method
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Syntax
static double random()
Eg
Public static void main (string args[])
{
Double ran;
ran= Math.random();
System.out.println (“The random no generated is: “ +
ran);
}
Absolute
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Syntax
static int abs(int num)
Eg
Public static void main (string args[])
{
Int no=4;
Int ran;
ran= Math.abs(no);
System.out.println (“The absolute value of no is: “ + ran);
}
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Syntax
static double sin (double angle)
Eg
Public static void main (string args[])
{
Double angle=30;
Double ran;
ran= Math.sin(angle);
System.out.println (“The value of sin( “+angle+”) is :“+
ran);
o/p The value of sin(30) is: 0.5
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Similarly we can find for tan,cos
Acos,asin,atan etc