I'd like to ask you a question about the code for creating a java lottery number

import java.util.*;
//lotto number
public class Pre4 {
public static void main(String[] args){
    Random rann = new Random();
    int[] a = new int[45];
    int[] b = new int[7];
    for(int q=0;q<a.length;q++){
        a[q]=q+1;
    }
    for(int w=0;w<7;w++){
        int r = rann.nextInt(45)+1;
        b[w]=a[r];
    }   
    System.out.print ("Results: ");
    for(int t=0;t<b.length;t++){
    System.out.print(b[t]+",");
    }
  }
}