Simple Program to print numbers using threads
NumberPrinter.java

public class NumberPrinter implements Runnable{
    int number;
    public NumberPrinter(int number){
        this.number = number;
    }

    public void run(){
        System.out.println("Printing Number from Thread "+ this.number);
    }
}

Main.java

public class Main {
    public static void main(String[] args) {
        for (int idx=1;idx<=5;idx++){
            Thread objthread = new Thread(new NumberPrinter(idx));
            objthread.start();
        }
    }
}

Output

Printing Number from Thread 5
Printing Number from Thread 1
Printing Number from Thread 4
Printing Number from Thread 3
Printing Number from Thread 2