Arnel Colar

Thanks. I'll read again that part of the book then simulate this code. Isn't it that:

while(x<9) is the counter and it will be put to m4a[x] then it increments until x<9 is met.

Am I correct?

Hi,

Can anyone explain to me this code. I got this problem while reading "HeadFirst Java 2nd Edition". I'm still dumb when it comes to arrays and loops.

Here is the code:
public class Mix4 { int counter = 0; public static void main(String[] args) { int count =0; Mix4[] m4a = new Mix4[20]; int x = 0; while (x < 9) { m4a[x] = new Mix4(); //1 m4a[x].counter = m4a[x].counter + 1; //1 count = count + 1; //2 count = count + m4a[x].maybeNew(x); x = x + 1; } System.out.println(count + " " + m4a[1].counter); } public int maybeNew(int index) { if (index < 5) { Mix4 m4 = new Mix4(); m4.counter = m4.counter + 1; return 1; } return 0; } }

And this is the output:
14 1

It will also be a great help if someone suggest websites or techniques on how I can easily understand loops and arrays especially when arrays are under a loop or they appear similar to the problem that I posted here. These are my weakness. I want to be able to surpass this so that I can progress more in Java programming.

Thanks Ralph. That explains some parts but why is it that when I remove d.snare = false i get this output:
bang bang ba-bang ding ding da-ding bang bang ba-bang

and when I bring back d.snare = false I get this output:
bang bang ba-bang ding ding da-ding

I'm sorry if my questions are a bit confusing to some. I'm a Java beginner and also new in forums. I'll be more specific with my questions next time.

Hi,

My first post was the given solution in that book. This is my answer:
My first attempt:
public class DrumKit { void playTopHat() { System.out.println("ding ding da-ding"); boolean topHat = true; } void playSnare() { System.out.println("bang bang ba-bang"); boolean snare = true; } } class DrumKitTestDrive { public static void main(String[] args) { DrumKit d = new DrumKit(); d.playSnare(); d.snare = false; d.playTopHat(); if (d.snare == true) { d.playSnare(); } } }

My second attempt was correct but:
public class DrumKit { boolean topHat; boolean snare; void playTopHat() { System.out.println("ding ding da-ding"); topHat = true; } void playSnare() { System.out.println("bang bang ba-bang"); snare = true; } } class DrumKitTestDrive { public static void main(String[] args) { DrumKit d = new DrumKit(); d.playSnare(); d.snare = false; d.playTopHat(); if (d.snare == true) { d.playSnare(); } } }

what confuses me is the solution in that book.

Hi,

I'm still confused how methods work. I am studying Java through Head First Java, a book that experienced Java developers suggests I begin my Java experience. I'm just in the Chapter 2 explaining methods when I came to this problem. Of course I tried my best to solve it but I got a wrong answer. So when I go to the solution page of the book, I got confused.

Here is what confuses me(I'll add comment on the part where I got confused):
public class DrumKit { boolean topHat = true; boolean snare = true; void playTopHat() { System.out.println("ding ding da-ding"); } void playSnare() { System.out.println("bang bang ba-bang"); } } class DrumKitTestDrive { public static void main(String[] args) { DrumKit d = new DrumKit(); d.playSnare(); d.snare = false; //this is the confusing part. d.playTopHat(); if (d.snare == true) { d.playSnare(); } } }

The confusing part is the boolean thing and the methods inside DrumKit class. How was it able to work even though it is not inside in any of the 2 methods. Ex. I figured that topHat should be inside playTopHat() method to work and the same with snare and playSnare().

Thank you all for the welcome and thank you for explaining the code. I thought I would look like a complete idiot asking that question (I get that a lot on OTHER Java forums). It looks like this will be favorite Java forum starting today.

I was doing an exercise here in javaranch to say a number. I finished it and yet it felt a bit cluttered and there are too many redundant codes so I asked for help. Many helped but there was one that caught my attention. This code:
import javax.swing.*; public class word { private static final String[] simple= { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "evelen", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eightteen", "nineteen" }; private static final String[] tens= { null, null, "twenty", "thirty", "fourty", "fifty", "sixty", "seventy", "eighty", "ninety" }; public static String say(int number) { return say(number, true); //default true } private static String say(int number, boolean sayZero) { if (number < 0) return "negative "+say(-number, sayZero); if (number == 0) return sayZero?simple[number]:""; if (number < 20) return simple[number]; if (number < 100) return tens[number/10]+say(number%10, false); if (number < 1000) return say(number/100, false)+" hundred "+say(number%100); if (number < 1000000) return say(number/1000, false)+" thousand"+say(number%1000, false); if (number < 1000000000) return say(number/1000000, false)+" million "+say(number%1000000, false); return say(number/1000000000, false)+"billion "+say(number%1000000000, false); } public static void main(String[] args) { String say = JOptionPane.showInputDialog("Enter a number"); int speak = Integer.parseInt(say); JOptionPane.showMessageDialog(null,say(speak)); } }

Every number I input works flawlessly. Then I got confused.. so here are my questions:
How did the say() method work?
Why is it that even if it is not on a loop the say() method works?
What is the role of boolean here?