What is the best way to split String in java, after every 4th an 3rd position?

Question

Note: My English is some thing poor

How to split String in java (every 4th and 3rd position).

For example, If i have a String of characters, as:

0110000 1100001 1001100 00110000 (without spaces, spaces are for only representations)

If, I want to split it as:

0110 000 1100 001 1001 100 0011 000 (without spaces)

How to do that in java?

I already have tried it as follows:

jshell> "01100001100001100110000110000".split("(?<=\\G.{4})");
$22 ==> String[8] { "0110", "0001", "1000", "0110", "0110", "0001", "1000", "0" }

As shown it split it into every 4th position not 4th position && 3rd position .

Also, Some thing that's

jshell> "01100001100001100110000110000".split("(?<=\\G.{4})|(?<=\\G.{3})");
$24 ==> String[10] { "011", "000", "011", "000", "011", "001", "100", "001", "100", "00" }

Or

jshell> "01100001100001100110000110000".split("(?<=\\G.{4}|\\G.{3})");
$25 ==> String[10] { "011", "000", "011", "000", "011", "001", "100", "001", "100", "00" }

Tried different ways but not not solved my problem. Also on the internet nothing find solution.

My question is that's how to solve this problem. Thanks.

Answer 1

You could first break the string in substrings of length 7 and process each of these substrings by splitting it after the 4th digit:

String string = "01100001100001100110000110000";
String[] array = string.split("(?<=\\G.{7})");
String[] array2= new String[array.length*2];

  for(int i = 0; i < array.length; i++) {
    String[] temp = array[i].split("(?<=\\G.{4})");
    array2[i*2] = temp[0];
    if (temp.length > 1) {
        array2[i*2+1]= temp[1];
    }
  }

Of course, you might want to add some additional math to skip the last "null"

array2 ==> String[10] { "0110", "000", "1100", "001", "1001", "100", "0011", "000", "0", null }

Answer 2

try this :

String a ="01100001100001100110000110000";
    List<String> stringList = new ArrayList();
    while (a.length()>=3)
    {
        if(a.length()>=4)
        {
            stringList.add(a.substring(0,4));
            a=a.substring(4,a.length());
            if(a.length()>=3)
            {
                stringList.add(a.substring(0,3));
                a=a.substring(3,a.length());
            }
        }
    }
    stringList.forEach(s-> System.out.println(s));

Answer 3

In latest Java version (eg java 11), You can write short method as follows:

void btnEncryptOnAction(ActionEvent event) {
var input = "01100001100001100110000110000";
String[] parts = input.split("(?<=\\G.{7})");
for (var p : parts) {
    String[] p2 = p.split("(?<=\\G.{4})");
    System.out.print(Arrays.asList(p2)); // to print as array list
}

The output is:

[0110, 000][1100, 001][1001, 100][0011, 000][0]