/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		String key = "A_B_C_D";       // => [A, B, C, D]
		//String key = "A_B_C_D_E_F"; // => [A_B, C, D, E, F]
		String[] res = null;
		if (key.split("_").length > 4) {
			res = key.split("(?<!^[^_]*)_");
		} else {
			res = key.split("_");
		}
		System.out.println(Arrays.toString(res));
	}
}

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