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Not complicated code

Although the code in Listing 8 is long and tedious, it isn't particularly complicated. It consists mainly of calls tothe accessor methods of the two sprite objects involved in the collision to modify their property values in some way.

Turn a green sprite into a blue sprite

For example, near the top of Listing 8 , there is a call to the setImage method of the green sprite to change it to a blue sprite.

Kill the green sprite

This is followed by a call to the setLife method to set the life of the (now blue) sprite object to 0, but only if the dieOnCollision variable belonging to the object is true. Later on, all sprite objects with a life property value of 0 will be removed from the population.

And so forth

I could continue down the page describing the calls to various other accessor methods, but that shouldn't be necessary. The embedded comments should sufficefor the explanation.

Play a sound

Finally near the end of the code in Listing 8 , there is a call to the play method belonging to Sound object referred to as blaster .

Each time there is a collision between the red sprite and a green sprite, the sound loaded earlier from the file named "blaster.wav" is played.

The end of the for loop

Listing 8 signals the end of the for loop, but does not signal the end of the update method. There is one more task to complete before the update method terminates.

Remove dead objects from the ArrayList object

The code in Listing 9 uses an Iterator to remove all objects having a life property value that is less than or equal to zero from the ArrayList object.

Listing 9 . Remove dead objects from the ArrayList object.
//Remove dead objects from the ArrayList objectIterator<Sprite01>iter = sprites.iterator(); while(iter.hasNext()){Sprite01 theSprite = iter.next(); if(theSprite.getLife()<= 0){ iter.remove();}//end if }//end while loop}//end update

Explanation of an Iterator

The explanation of an Iterator is beyond the scope of this module. However, if you Google the keywords baldwin java iterator , you will find several tutorials that I have published on this and related topics.

Listing 9 signals the end of the update method.

The render method

The render method is shown in Listing 10 . There is nothing new in this code.

Listing 10 . The render method.
public void render(GameContainer gc, Graphics g) throws SlickException{//set the drawing mode to honor transparent pixels g.setDrawMode(g.MODE_NORMAL);//Draw the background to erase the previous picture. background.draw(0,0);//Draw every sprite in the ArrayList object. for(int cnt = 0;cnt<sprites.size();cnt++){ sprites.get(cnt).draw();}//end for loop//Display the remaining number of sprites. g.drawString("Sprites remaining: " + (sprites.size()),100f,10f); //Signal when all sprites have been eaten.if(sprites.size() == 1){ g.drawString("Burp!",100f,25f);}//end if }//end render}//end class Slick0210 //======================================================//

The end of the class

Questions & Answers

WHAT IS QUADRATIC EQUATION?
Charles Reply
WHAT IS SYSTEM OF LINEAR INEWUALITIES?
Charles
WHAT IS SYSTEM OF LINEAR INEWUALITIES?
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The 47th problem of Euclid
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show that the set of all natural number form semi group under the composition of addition
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explain and give four Example hyperbolic function
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_3_2_1
felecia
⅗ ⅔½
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_½+⅔-¾
felecia
The denominator of a certain fraction is 9 more than the numerator. If 6 is added to both terms of the fraction, the value of the fraction becomes 2/3. Find the original fraction. 2. The sum of the least and greatest of 3 consecutive integers is 60. What are the valu
SABAL Reply
1. x + 6 2 -------------- = _ x + 9 + 6 3 x + 6 3 ----------- x -- (cross multiply) x + 15 2 3(x + 6) = 2(x + 15) 3x + 18 = 2x + 30 (-2x from both) x + 18 = 30 (-18 from both) x = 12 Test: 12 + 6 18 2 -------------- = --- = --- 12 + 9 + 6 27 3
Pawel
2. (x) + (x + 2) = 60 2x + 2 = 60 2x = 58 x = 29 29, 30, & 31
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Ifeanyi
on number 2 question How did you got 2x +2
Ifeanyi
combine like terms. x + x + 2 is same as 2x + 2
Pawel
x*x=2
felecia
2+2x=
felecia
×/×+9+6/1
Debbie
Q2 x+(x+2)+(x+4)=60 3x+6=60 3x+6-6=60-6 3x=54 3x/3=54/3 x=18 :. The numbers are 18,20 and 22
Naagmenkoma
Mark and Don are planning to sell each of their marble collections at a garage sale. If Don has 1 more than 3 times the number of marbles Mark has, how many does each boy have to sell if the total number of marbles is 113?
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Mark = x,. Don = 3x + 1 x + 3x + 1 = 113 4x = 112, x = 28 Mark = 28, Don = 85, 28 + 85 = 113
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find the value of 2x=32
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divide by 2 on each side of the equal sign to solve for x
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X=16
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16
Makan
x=16
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use the y -intercept and slope to sketch the graph of the equation y=6x
Only Reply
how do we prove the quadratic formular
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4
Trista
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
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Mark
Solve for the first variable in one of the equations, then substitute the result into the other equation. Point For: (6111,4111,−411)(6111,4111,-411) Equation Form: x=6111,y=4111,z=−411x=6111,y=4111,z=-411
Brenna
(61/11,41/11,−4/11)
Brenna
x=61/11 y=41/11 z=−4/11 x=61/11 y=41/11 z=-4/11
Brenna
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Source:  OpenStax, Anatomy of a game engine. OpenStax CNX. Feb 07, 2013 Download for free at https://legacy.cnx.org/content/col11489/1.13
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