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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. Public class key { Public static void main(String args) { String name;

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LAB SESSION-5

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  1. LAB SESSION-5 Topics covered User input using keyboard. java User input using JoptionPane Arithmetic expression……………. Math class…………………………… Testing………………………………….

  2. Eg of keyboard. java • 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

  3. JOPTION PANE • Eg program import javax.swing.*; Public class AsampleGuiProgram { Public static void main(String args[]) { String name; String temp; Int age; 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

  4. 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

  5. Arithmetic expression • 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

  6. Result=14+8/2; ans=18 ans=11 correct ans is 18 operator precedence hierarchy division/multiplication/% add/sub /concatenation assignment

  7. 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

  8. 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

  9. MATH CLASS • 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

  10. 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

  11. Power method • 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

  12. Exponent • 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

  13. Random method • 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); }

  14. Absolute • 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); }

  15. 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

  16. Similarly we can find for tan,cos • Acos,asin,atan etc

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