/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.stream.*;
/* 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> values = new ArrayList<>();
		values.add("1000");
		values.add("10001111");
		values.add("45678901");
		values.add("1111");
		values.add("22222222");
		values.add("2222");
		values.add("33333333");
		List<Integer> indexes = new ArrayList<>();
		for(int i=0; i<values.size();i++){
			if(values.get(i).length() == 4){
				indexes.add(i);
			}
		}
		System.out.println(indexes);
	}
}

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