Code for creating string in a loop to report numbers - string

Question

I created a code that functions as it is supposed to. I determined the escape function to be -1 for the user to exit the program and used if/else to only add the sum of positive integers.
I know that I have to save the numbers that pass the if statement (only positive numbers) and the only way that I can think of doing this is through a String.
Unfortunately, whenever I attempt to add a string as part of the while loop, it will print the statement over and over again when I only want a single line.
I'm also struggling to set the user input to a single line. I know it has everything to do with the .nextLine() command, but if I pull it outside the brackets (which I've attempted to do) then it reads as an error.
Actually, a source about conversion of Strings to characters or inputs to Strings would be very helpful as well. It's apparent that this is where a good portion of my understanding is lacking.
public static void main(String args[])
{
int userNum = 0;
int sum = 0;
Scanner s = new Scanner(System.in);
String str3;
System.out.print("Enter positive integers (to exit enter -1):\n ");
//Loop for adding sum with exit -1
while(userNum != -1){
//condition to only calculate positive numbers user entered
if(userNum > 0){
//calculation of all positive numbers user entered
sum += userNum;
str3 = String.valueOf(userNum);}
userNum = s.nextInt();
}
System.out.println("The values of the sum are: " + str3);
System.out.println("The Sum: " + sum);
}
}
I'm hoping for the user input to be printed,
Enter positive integers (to exit enter -1): _ _ ___//with the user
input in the same row.
And...
values from string to read out on same line, not multiple lines.

Answer 1

The variable str needs to be initialized as:
String str3 = "";
and in the loop, each entered number must be concatenated to str.
int userNum = 0;
int sum = 0;
Scanner s = new Scanner(System.in);
String str3 = "";
System.out.print("Enter positive integers (to exit enter -1):\n ");
while (userNum != -1) {
userNum = s.nextInt();
if (userNum > 0) {
sum += userNum;
str3 += " " + userNum;
}
}
System.out.println("The values of the sum are: " + str3);
System.out.println("The Sum: " + sum);