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Types of Control Flow Flow of control through any given function is implemented with three basic types of control structures: I Sequential: Default mode. Statements are executed line by line. I Selection: Used for decisions, branching { choosing between 2 or more alternative paths. I if I if - else I switch I conditional statements
Java's branching control uses the if-else structure (http://docs.oracle.com/javase/tutorial/java/nutsandbolts/if.html) for selecting which blocks of code should run. The if-statement by itself lets us choose whether or not to run a block of code: if ( boolExpr ) { // run these statements only if boolExpr was true; otherwise, skip. }
As we saw when studying Python in Chaps. 3 and 4, the two alternative forms of control available to programmers are selection (making choices in programs) and iteration (repeating a section of code numerous times). Both of these forms of control are available in Java with very similar syntax to Python.
4.4 Control Structures • Java has a sequence structure “built-in” • Java provides three selection structures – if – If…else – switch • Java provides three repetition structures – while – do…while – do • Each of these words is a Java keyword
Chapter 4: Selection Structures. Objectives. In this chapter, you will learn about: Selection criteria. The if-else statement. Nested if statements. The switch statement. Program testing. Common programming errors. Selection Criteria. • if-else statement: Implements a decision structure for two alternatives Syntax:
Control structures: selection, looping, etc. Object messages: i.e., calls to methods A Java application always executes the main method
Using Selection: the CoinExample Class • if statement based on using a randomly generated number to represent a coin being flipped • The Java Math class random operation –Returns a random double >= 0.0 and < 1.0 • Use random number in if statement 10 double randomNumber = Math.random(); if (randomNumber < 0.5) {
