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10/9: the switch selection structure • looking at Interest.java – use of postincrement – Math.pow( 1.0 + rate, year ) – JTextArea • switch multiple-selection structure Interest.java: use of postincrement • for ( int year = 1 ; year <= 10 ; year++ ) – would a change to a preincrement cause a changed output? – No, because it executes like it is the only thing happening in a statement: year++ ; Interest.java: Math.pow • Math.pow( 1.0 + rate, year ); – Math class method Math.pow( x , y ); y – calculates x to the y power: x – listed in the java.lang.Math library Interest.java: JTextArea • JTextArea: a type of output area. • we create a new object ( outputTextArea ) as an instance of the class JTextArea: instantiation. • associated method: append – means add onto the JTextArea some type of String output. – the append method works similarly to saying result = result + “\n” + x + “ dollars”; (EX) • View more info about JTextArea at java.sun.com the switch multiple-selection structure • previously selection structures: if, if/else switch ( pizzaSlice ) { case 1: System.out.print ( "Take more" ); break; case 2: System.out.print ( “Just right” ); break; default: System.out.print ( "Have some pizza, man!" ); break; switch multiple selection structure • consists of cases with labels, including the default case • break exits the structure • controlling variable’s value – compared to each case label – if no match, the default case is executed • can handle integers Today’s Program: p. 170 SwitchTest • after you get it to work, modify the program: – Ask first for a color ( pick 3 colors: black, blue, cyan, darkGray, gray, lightGray, green, magenta, orange, pink, red, white, yellow ) to use in the next step. You must import the java.awt.Color class. Use the following statement example to set the color: g.setColor ( Color.yellow ); – Then ask the user for their choice of lines, hollow rectangles, filled rectangles, hollow ovals, and filled ovals. applicable methods: drawLine, drawRect, fillRect, drawOval, fillOval.