А что не так? Все выводится и работает..
package com.javarush.task.task16.task1629;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class Solution {
public static volatile BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
public static void main(String[] args) throws InterruptedException {
Read3Strings t1 = new Read3Strings();
Read3Strings t2 = new Read3Strings();
t1.start();
t2.start();
t1.join();
t2.join();
//add your code here - добавьте код тут
t1.printResult();
t2.printResult();
}
public static class Read3Strings extends Thread {
public String out;
@Override
public void run() {
try {
String l1 = reader.readLine();
String l2 = reader.readLine();
String l3 = reader.readLine();
out = l1 + " " + l2 + " " + l3;
} catch (Exception e) {
e.printStackTrace();
}
}
public String printResult() {
System.out.println(out);
return null;
}
}
//add your code here - добавьте код тут
}