Objectives
Review of variables
What is a boolean expression?
Testing a condition
:
Examples:
Not operator
Loops
Types of Loops:
While loop
Move until you reach a wall
Pick up a pile of beepers
Go until you reach the wall, pick up beepers along the way
For loops: when we know how many iterations – how many times we want to repeat the loop.
Put down 5 beepers:
-
Initialize a variable k
-
Loop while k < 5
-
Increment k by 1 after each iteration.
Write an instance method to move a specified number of times.
| -
I will be able to implement an if statement.
-
I will be able to implement a while loop.
-
I will be able to implement a for loop.
Declare an integer called count with an initial value of 0
int count = 0;
Increment the count by 1
count = count + 1
or: count++
Declare an boolean called result with an initial value of true
Boolean result = true;
count < 5 - it evaluates to either true or false
result
if (boolean – expression)
{
Code body
}
if (boolean-expression)
System.out.println(“It’s true”);
else
System.out.println(“It’s false”);
if (karel.frontIsClear() )
karel.move();
if (karel.nextToABeeper() )
karel.pickBeeper();
!false = true
if ( ! karel.frontIsClear() )
karel.turnLeft();
When we want to do things multiple number of times.
-
Based on a condition: ex. While the front is clear, keep moving
-
Based on a count: move 5 spaces
2 types of loops we will cover in this class:
while (boolean-expression)
{
Code – body - if more than 1 statement, curly braces are required.
}
while (karel.frontIsClear() )
karel.move();
while (karel.nextToABeeper() )
karel.pickBeeper();
while (karel.frontIsClear() )
{
if ( karel.nextToABeeper() )
karel.pickBeeper();
karel.move();
}
for ( initial – condition ; loop continuation condition ; end of loop statement )
{
Code – body - if more than 1 statement, curly braces are required.
}
for (int k=0; k < 5; k++)
karel.putBeeper();
public class Racer extends Athlete
{
public void sprint ( int n )
{
for (int k = 0; k < n ; k++ )
move();
}
Racer:
sprint( int n )
put ( int n)
pick (int n)
jumpRight ()
jumpLeft ()
|