Chapter 5 Functional Methods

© Daly and Wrigley Learning Java through Alice Objectives Properly construct and use methods when programming. Describe the difference between a procedural method and a functional method. Use the Java Application Interface to code programs. Place methods into a separate file and call them from the main program. 2

© Daly and Wrigley Learning Java through Alice JOptionPane 3

© Daly and Wrigley Learning Java through Alice Math Class Method DescriptionMethod CallResultArgumentReturns Returns the absolute valueMath.abs(-5.5);5.5double Returns the value of the first argument raised to the power of the second argument Math.pow(5, 2);25 double, double double Returns a positive number that is greater than or equal to 0.0 and less than 1.0. Math.random( ); Number between 0 and 1 nonedouble Returns the closest whole number to the argument Math.round(6.45);6double Returns the rounded positive square root Math.sqrt(7); double 4

© Daly and Wrigley Learning Java through Alice String Methods String s1 = "Now is the winter of our discontent"; String s2 = "Java can be fun and hard "; MethodResult s1.length( )35 s2.length( )25 s1.toUpperCase()NOW IS THE WINTER OF OUR DISCONTENT s2.toUpperCase()JAVA CAN BE FUN AND HARD s1.toLowerCase()now is the winter of our discontent s2.toLowerCase()java can be fun and hard s1.startsWith("st")False s2.startsWith("Java")true 5

© Daly and Wrigley Learning Java through Alice String Methods String s1 = "Now is the winter of our discontent"; String s2 = "Java can be fun and hard "; MethodResult s1.endsWith(“TENT")false s2.endsWith("so")false s1.replace( 'e','L' )Now is thL wintLr of our discontLnt s2.replace( 'a', '*' )J*v* c*n be fun *nd h*rd s1.equals(s2)false s1.equalsIgnoreCase(s2)false s1.contains("winter")true 6

© Daly and Wrigley Learning Java through Alice Comparing Objects vs Primitives 7

© Daly and Wrigley Learning Java through Alice String Comparisons 8

© Daly and Wrigley Learning Java through Alice String Comparisons 9

© Daly and Wrigley Learning Java through Alice String Tokenizer String s1 = "Now is the winter of our discontent"; StringTokenizer tokens = new StringTokenizer(s1); int x = tokens.countTokens(); Need following import: ▫ import java.util.StringTokenizer; Breaks up strings into pieces called tokens Tokens are separated by whitespace characters such as blanks, tabs, newlines, and carriage returns. 10

© Daly and Wrigley Learning Java through Alice Alice Functional Methods 11

© Daly and Wrigley Learning Java through Alice Method with Arguments & Return Value 12