Download Lesson 1.4 Decision and looping structures File

ICS2O Decision and looping structures
Topics: Decision and looping structures
Curriculum expectations:
B1.5 identify situations in which decision and looping structures are required;
Resources/Materials required:
https://docs.oracle.com/javase/tutorial/java/nutsandbolts/if.html
Lecture: Decision and looping structures
The if-then and if-then-else Statements
The if-then statement is the most basic of all the control flow statements. It tells your program to execute a
certain section of code only if a particular test evaluates to true.
Int x=10;
If (x>0){
System.out.println(“x is positive”);
}
else{
System.out.println(“x is negative”);
}
-------------------------------------public class TestNumber{
public static void main(String[] args){
double x=Double.parseDouble(args[0]);
if (x>0){
System.out.println(x+ " is positive");
}
else{
System.out.println(x+ " is negative");
}
}
}
Activity:
Type, compile and execute the following program
The switch Statement
Unlike if-then and if-then-else statements, the switch statement can have a number of possible
execution paths. A switch works with the byte, short, char, and int primitive data types. It also works
with enumerated types (discussed in Enum Types), the String class, and a few special classes that
wrap certain primitive types: Character, Byte, Short, and Integer
-------------------------------------------
The while and do-while Statements
The while statement continually executes a block of statements while a particular condition is true.
Its syntax can be expressed as:
while (expression) {
statement(s)
}
The for Statement
The for statement provides a compact way to iterate over a range of values. Programmers
often refer to it as the "for loop" because of the way in which it repeatedly loops until a
particular condition is satisfied. The general form of the for statement can be expressed as
follows:
for (initialization; termination;
increment) {
statement(s)
}
Homework:
1. Write a Calculator which can calculate any two numbers based on “ + - * /”
For example:
Input: java Calculator 3 + 2
Output: 3+2=5
Input: java Calculator 3 - 2
Output: 3-2=1
Input: java Calculator 3 / 2
Output: 3 / 2=1.5
Input: java Calculator 3 * 2
Output: 3 * 2=6
Teaching Strategies:
Direct Instruction (teacher-led)
*
Class Activity (teacher facilitation)
Direct Instruction (discussion possible)
*
Experiential learning (learn by doing)
Class Discussion (teacher facilitated)
Worksheets/Surveys
Small Group Discussion
Individual or Group Research
Partner Discussion/Conferencing
Teacher Modeling
1:1 Conferencing Teacher & Student.
Text-based modeling
Teacher reading to class
Use of Computers / Internet
Silent individual reading
Use of video tape or audio materials
*
*
Group based reading
Role Playing
Independent Work (teacher facilitation)
Presentations.
Group Work (teacher facilitation)
Guest Speaker / Interviews / Questions