Java Karel's Built in Commands

move();

turnLeft();

putBall();

takeBall();

Methods

Writing a method is like teaching karel a new word.

Naming Methods: You can name your methods whatever you want, but you can't have spaces in the method name.

Remember that each open bracket { must match with a close bracket }

private void turnRight()
{
    turnLeft();
    turnLeft();
    turnLeft();
}

private void turnAround()
{
    turnLeft();
    turnLeft();
}

private void yourMethodName()
{
  // Code that will run when you make a call to
  // this method.
}

Conditional Statements

if (condition) 
{
  //code that will run if the condition is true
}

if (condition) 
{
  //code that will run if the condition is true
}
else
{
  //code that will run if condition is not true
}

Example of if statements

if(frontIsClear())
{
  move();
}

if(ballsPresent())
{
  takeBall();
}
else
{
  move();
}

Karel Conditions

frontIsClear()
leftIsClear()
rightIsClear()

facingNorth()
facingSouth()
facingEast()
facingWest()

ballsPresent()
            

frontIsBlocked()
leftIsBlocked()
rightIsBlocked()

notFacingNorth()
notFacingSouth()
notFacingEast()
notFacingWest()

noBallsPresent()
            

Loops

While Loops

while (CONDITION)
{
  // Code that will run while the CONDITION is true.
  // Once the CONDITION is no longer true,
  // it will stop.
}

Example of while loops

/* This moves Karel to a wall */
while(frontIsClear())
{
    move();
}

For Loops

for (int i=0; i < COUNT; i++)
{
  // Code that will run 'COUNT' times
}

Example of for loops

/* This puts down 10 balls */
for(int i = 0; i < 10; i++)
{
    putBall();
}

/* This puts down five balls and
   moves after each one */
for(int i = 0; i < 5; i++)
{
    putBall();
    move();
}

Comments

/* A multi-line comment describes your code
 * to someone who is reading it. */

// Use single line comments to clarify code.

/**
 *
 * A Javadoc comment
 * is used to describe how a
 * method or class works.
 *
 * It has two *'s on the first line.
 */

Slides and Notes

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