如何在Android中每2个字符后将特殊符号连接为冒号

Question

I want to concatenate or append special character as colon : after an every 2 character in String.

For Example: Original String are as follow:

String abc =AABBCCDDEEFF;

After concatenate or append colon are as follow:

  String abc =AA:BB:CC:DD:EE:FF;

So my question is how we can achieve this in android.

Thanks in advance.

Answer 1

In Kotlin use chunked(2) to split the String every 2 chars and rejoin with joinToString(":") :

val str = "AABBCCDDEEFF"
val newstr = str.chunked(2).joinToString(":")
println(newstr)

will print

AA:BB:CC:DD:EE:FF

Answer 2

Use a StringBuilder :

StringBuilder sb = new StringBuilder(abc.length() * 3 / 2);
String delim = "";
for (int i = 0; i < abc.length(); i += 2) {
  sb.append(delim);
  sb.append(abc, i, Math.min(i + 2, abc.length()));
  delim = ":";
}
String newAbc = sb.toString();

Answer 3

You can try below code, if you want to do without Math class functions.

StringBuilder stringBuilder = new StringBuilder();
    for (int a =0; a < abc.length(); a++) {
        stringBuilder.append(abc.charAt(a));
        if (a % 2 == 1 && a < abc.length() -1)
            stringBuilder.append(":");
    }

Here

1. a % 2 == 1 ** ==> this conditional statement is used to append **":"
2. a < abc.length() -1 ==> this conditional statement is used not to add ":"

in last entry. Hope this makes sense. If you found any problem please let me know.

Answer 4

Here is the Kotlin way. without StringBuilder

val newString: String = abc.toCharArray().mapIndexed { index, c ->
            if (index % 2 == 1 && index < abc.length - 1) {
                "$c:"
            } else {
                c
            }
        }.joinToString("")

Answer 5

You can combine String.split and String.join ( TextUtils.join(":", someList) for android) to first split the string at each second char and join it using the delimiter you want. Example:

String abc = "AABBCCDDEEFF";
String def = String.join(":", abc.split("(?<=\\G.{2})"));
System.out.println(def);
//AA:BB:CC:DD:EE:FF