Building Java Programs Chapter 2

1. Building Java ProgramsChapter 2 Primitive Data and Definite Loops

2. Review • Primitive data types: boolean, char, double, int • Expressions and literals • Arithmetic operators: +, -, *, /, % • Precedence and casting • Variables • String concatenation and mixing types • Increment/decrement operators • For loops

3. Review • What output by the following set of statements? • int x = 12; • double y = 24; • System.out.println("x divided by y = " + x / y); • A. x divided by y = 0 • B. x divided by y = 12 / 24 • C. x divided by y = 0.5 • D. x divided by y = + 12 / 24 • E. Nothing – this does not compile.

4. header body for loop syntax for (initialization; test; update) { statement; statement; ... statement; } Perform initialization once. Repeat the following: • Check if the test is true. If not, stop. • Execute the statements. • Perform the update.

6. Repetition with for loops We see redundancy when trying to perform a task more than once: System.out.println(“Let’s go…"); System.out.println(“Seahawks!"); System.out.println(“Seahawks!"); System.out.println(“Seahawks!"); System.out.println(“Go home, Peyton!"); Java's for loop statement performs a task many times. System.out.println(“Let’s go…"); // Repeat 3 times for (inti = 0; i <= 2; i++) { System.out.println(“Seahawks!"); } System.out.println(“Go home, Peyton!");

7. Volunteers Initializer Condition tester Console Updater Variable

8. for (intcandies = 0; candies < 5; candies++) { System.out.println("I ate " + candies + " candies"); }

9. Practice-It • Self-check: 2.12, 2.15, 2.16, 2.18, 2.20

10. Nested for loops One for loop can be nested inside another. for(intouterLoop = 0; outerLoop < 2; outerLoop++) { System.out.println("OuterLoop variable = " + outerLoop); for (intinnerLoop = 5; innerLoop > 0; innerLoop = innerLoop / 2) { System.out.println("InnerLoop variable = " + innerLoop); } }

11. Nested for loops for (intouterLoop = 0; outerLoop < 2; outerLoop++) { System.out.println("OuterLoop variable = " + outerLoop); for (intinnerLoop = 5; innerLoop > 0; innerLoop = innerLoop / 2) { System.out.println("InnerLoop variable = " + innerLoop); } } • OuterLoopvariable = 0 • InnerLoop variable = 5 • InnerLoop variable = 2 • InnerLoop variable = 1 • OuterLoop variable = 1 • InnerLoop variable = 5 • InnerLoop variable = 2 • InnerLoop variable = 1

12. Homework Self-check: 2.12, 2.15, 2.16, 2.18, 2.20, 2.26, 2.27 Exercise: 2.2, 2.3 If you finish the homework before class is over: • Review for your quiz on Wednesday. • Read BJP 2.4. • Do extra Practice-Its.