Why can't I print the String out of my multidimensional-Array?

Question

I've read in other posts, that instead of writing just System.out.println(finalPressedKey); you should write System.out.println(Arrays.toString((finalPressedKey)); because otherwise it will just return the location where the String is saved (as far as I understood it).

public static String PressedKey[] = new String[2000];

public static String[][] finalPressedKey = {{ "", "", "", "", "", "", "", "", "", "", "", "" }}; // 12

public static String FPK3;

public static void upcounter(KeyEvent e) {

    for (int x = 0; x < PressedKey.length; x++) {

        if (PressedKey[x] != null && PressedKey[x + counter] != null) {

        //FPK counter is supposed to be a line, and counter is where the words are supposed to be saved

        finalPressedKey[FPKcounter][counter] =
        finalPressedKey[FPKcounter] + PressedKey[x + counter];

            System.out.println(Arrays.toString(finalPressedKey));
        }

    }

Whenever I Press a Button, it should be saved in my PressedKey Array, and finalPressedKey is supposed to contain itself, and PressedKey (also , only the last element of the array is supposed to be printed), but instead it just prints [[Ljava.lang.String;@76f42c4b]

I also tried using Arrays.deepToString(); but it gives me the same output as with Arrays.toString();

Thanks for your help!

Answer 1

A String[][] is not a 2-d array. It is an array of String[] . The difference is subtle but important.

The method Arrays.toString() takes an array, iterates through its elements, calls toString() on all of them, and adds a prefix, suffix, and delimiters. Since you give it a String[][] (an array of String[] ), it will do the following:

• Iterate through the elements (each of them a String[] )
• call toString() on each element - giving the default toString() value of an array - ie its memory address (not really but for this purpose it doesn't matter)
• concatenate

Luckily for you, there is an easier way - just use Arrays.deepToString() . This behaves as you would expect.

Answer 2

I did not understand the whole code, but following statement is very suspicious:

finalPressedKey[FPKcounter][counter] =
finalPressedKey[FPKcounter] + PressedKey[x + counter];

since it is adding an array ( finalPressedKey[...] ) to a string ( PressedKey[...] ), which will result in that strange text - the standard textual representation of an array (returned by toString ). (from a mathematical point of view , it's strange to have 2 indexes )2D_ before the assignment and only one on the right side (1D) for same matrix)

I'm not sure, since we cannot see what counter is, but I believe you wanted something like:

finalPressedKey[FPKcounter][counter] =
finalPressedKey[FPKcounter][counter] + PressedKey[x + counter];

that is, an additional [counter] on second line.

This can also be written as

finalPressedKey[FPKcounter][counter] += PressedKey[x + counter];

Answer 3

You have to print the elements of your array with

for(int i = 0; i<finalPressedKey[0].length; i++){
   for(int j=0; j<finalPressedKey[1].length; j++){
      System.out.println(finalPressedKey[i][j]);
   } 
}

if I understand it correctly.

Answer 4

If you only want to store lines of strings, a normal String[] is good for you

finalPressedKey[FPKcounter] += PressedKey[x + counter];

even though I wouldn't recomment doing this, no matter what you're trying to accomplish, since this will create a new String object each time a key is pressed.

Maybe ask the question differently and tell us what you're trying to do. I guess String arrays might not be the way to go.