Arrays

[Droid_X]

For some reason I get an error on line 12 where I access the array and print all the values.

public class blah {
	public static String[][][] arr = new String[][][]{
		{{"Hello1","Bye1"},{"Hello2","Bye2"}},
		{{"Hello3","Bye3"},{"Hello4","Bye4"}},
		{{"Hello5","Bye5"},{"Hello6","Bye6"}},
		{{"Hello7","Bye7"},{"Hello8","Bye8"}},
	};
	public static void main(String args[]){
		for (int x = 0; x <= arr.length; x++) {
			for (int y = 0; y <= arr[x].length; y++){
				for (int z = 0; z <= arr[y].length; z++){
					System.out.println(arr[x][y][z]); // On this line.
					try {
						 Thread.sleep(50);
					} 
					catch(InterruptedException e) {
					} 
				}
			}
		}
	}
}

[pbrockway2]

What is the exception? If you can't understand it, copy and post the entire stack trace.

[Droid_X]

Stack trace?

[Droid_X]

I found the answer.

I was learning Lua previously and the tables/arrays in Lua begin with index 1 instead of 0.

public class blah {
	public static String[][][] arr = new String[][][]{
		{{"Hello1","Bye1"},{"Hello2","Bye2"}},
		{{"Hello3","Bye3"},{"Hello4","Bye4"}},
		{{"Hello5","Bye5"},{"Hello6","Bye6"}},
		{{"Hello7","Bye7"},{"Hello8","Bye8"}},
	};
	public static void main(String args[]){
		for (int x = 0; x < arr.length; x++) {
			for (int y = 0; y < arr[x].length; y++){
				for (int z = 0; z < arr[y].length; z++){
					System.out.println(arr[x][y][z]);
					try {
						 Thread.sleep(50);
					} 
					catch(InterruptedException e) {
					} 
				}
			}
		}
	}
}

[pbrockway2]

I'm glad you've got it sorted out.

By stack trace I meant the descriptive output that the runtime produces when something goes wrong:

C:\Users\Educator\Desktop>javac -cp . Blah.java

C:\Users\Educator\Desktop>java -cp . Blah
Hello1
Bye1
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2
        at Blah.main(Blah.java:12)

C:\Users\Educator\Desktop>

Not very long stack trace on this occasion, but "ArrayIndexOutOfBoundsException" is quite useful. The number 2 indicates the value that the runtime was objecting to. In this case you would have to output the values of x, y and z to see which one was out of bounds.

Notice that you'll get the exception again if you replace your array with:

public static String[][][] arr = new String[][][]{
    {{"Hello1","Bye1"},{"Hello2","Bye2"},{"Hello2b","Bye2b"}},
    {{"Hello3","Bye3"},{"Hello4","Bye4"},{"Hello4b","Bye4b"}},
    {{"Hello5","Bye5"},{"Hello6","Bye6"},{"Hello6b","Bye6b"}},
    {{"Hello7","Bye7"},{"Hello8","Bye8"},{"Hello8b","Bye8b"}},
};

[Droid_X]

And how would I make it so I don't get an error with that array you gave?

[pbrockway2]

And how would I make it so I don't get an error with that array you gave?

As I suggested, by printing out the values of x, y and z just before the error occurs in order to see which one is out of bounds. Once you've determined that you can go back through your code and check the line that assigned that value.

[jim829]

You might try it this way instead, since arrays are iterable. That way
you don't have to worry about array lengths (and its just cleaner).

Also, unless you have a compelling reason to use arrays, you should probably
use Lists or some other form of Collection.

/r,
Jim

public class Blah {
   public static String[][][] arr = new String[][][]{
       {{"Hello1","Bye1"},{"Hello2","Bye2"}},
       {{"Hello3","Bye3"},{"Hello4","Bye4"}},
       {{"Hello5","Bye5"},{"Hello6","Bye6"}},
       {{"Hello7","Bye7"},{"Hello8","Bye8"}},
   };
   public static void main(String args[]){
       for (String [][] a : arr) {
          for (String [] b : a) {
             for (String c : b) { 
                System.out.println(c);
             }
          }
       }
   }
}