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#1 2017-01-28 11:35:47

Hannibal lecter
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Registered: 2016-02-11
Posts: 138
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I need to learn java language "Arrays",..

Hi I need to learn java language "Arrays"
from zero, cause I don't know how to use arrays I'mm fully not understaing this topic in java


Wisdom is a tree which grows in the heart and fruits on the tongue

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#2 2017-07-29 02:39:50

Jabuto
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Registered: 2017-07-29
Posts: 6

Re: I need to learn java language "Arrays",..

they are quite simple actually, in my opinion at least.

  int x = 1;  // regular integer

  int[] y;     // an integer array! it is still just an empty name...

  y = new int[5];   // we put a fresh array length of length 5 to it. think of box with exactly 5 slots for ints.

  y[0] = 11;    // we can access the 5 slots with "index". indexes start from zero. (so 0,1,2,3 and 4 are valid).

  y = new int[99]; // we erase the current array and create new one, as size cannot change in-between.

  for(int i=0; i<y.length; i++){  y[i] = i+1; }   // we put numbers 1-99 to the array.

  try{  y[100] = 0; } // watch here, we access 101th slot in the array, which does not exist.
  catch(IndexOutOfBoundsException){}   // an error will be raised. be careful with this.

  string[] z; // string array is as fine as any other...

  myObject[] mo;   // any obeject can form an array!

  bool[,] b = new bool[10,10] // a fancy, two-dimensional array! it works like other arrays, but you must give two indexes to access "a slot".

  bool[,,,] bbb = new bool[2,4,6,8]; // while this is legit, it may use lots of space.

  int[][] ii = new int[5][]; // an array of array of ints! box, which contains boxes, which contain ints.

  ii[0] = new int[4]   // a new box to a box.

  ii[0][0] // a number to box inside box.

arrays have also many useful built-in methods which you can search from the manual.


life←{↑1 ⍵∨.∧3 4=+/,¯1 0 1∘.⊖¯1 0 1∘.⌽⊂⍵}

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