/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.*;
/* 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
	{
		List<String> strs = Arrays.asList("123456", "12345 ", " 23456", "     5", // good
		"1     ", "      ", "  2   ", " 2345 ",  // good
		"12 456", "1234 6", " 1   6", "1    6"); // bad
		for (String str : strs)
			System.out.println(str.matches("(?=.{6}$) *\\d* *"));
 
	}
}

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