Help with a basic Java program?

just a guide, don’t know java
correct the syntax and stuff and this should be your loop.

INPUT=B

for(A=1; A=<B; A=A+1){
for(a=A; a=>0; a=a-1){
print/echo/say ”*”;
}
print linebreak/</br>/
}

for(A=B; A=>0; A=A-1){
for(a=A; a=>0; a=a-1){
print/echo/say ”*”;
}
print linebreak/</br>/
}

The best way to approach a problem like this is to think about what each loop will do:

1. Print out a number of lines of asterisks.
2. Print out a number of asterisks for every line.

The statements above are clearly loops because they are doing something repeatedly, and they clearly indicate for loops because the number of iterations is known (5 in your example). The outer loop (#1 above) would look something like this:

for (int i = 0; i < num * 2; i ++) { ... }

And the inner loop (#2 above) would look something like this:

for (int j = 0; j < asterisk_count; j ++) { ... }

Now throw in the print statements. The code would look like this:

for (int i = 0; i < num * 2; i ++) {
    if (i > num)
        asterisk_count = num – (i % num);
    else
        asterisk_count = i + 1;
    for (int j = 0; j < asterisk_count; j ++) {
        print ”*”;
    }
    print ”\r\n”;
}

First loop: loop num * 2 number of times because you want to print out twice the number of lines as the number the user entered. In your example above, the user entered 5 and the program printed 10 lines. I noticed there’s an extra single asterisk line at the end. To get rid of that, you’d use (num * 2) – 1.

Second loop: Print the number of asterisks. asterisk_count will be set to 1 thru 5 for the first 5 iterations, then 5 to 1 for the next 5 iterations.

This solution only uses one set of nested for loops while @Zyx‘s answer uses two sets of two.