Delay Line of Code for X Amount of Seconds

Hi, all! This is my first post on this forum.

I’m working on my first game, and the basic objective is to collect as much trash as you can, but I’m having a little problem. To spawn the objects, I’m checking the level to see if it’s 1, 2, 3, etc. then spawn x amount of objects for that level. But, I don’t want them all to spawn at once, I want to delay part of the code for a certain time so the player can have a chance to catch them all.

Here is the code I’m talking about. http://pastebin.java-gaming.org/0660d2d05521e

Inside of the if statement, are 2 separate sections of code, that spawn the objects, how can I delay the second part by a few seconds. I’ve googled it, but all I can find are people saying to put the thread to sleep, but I don’t want to stop the game completely, just delay a section of code.

Any help is appreciated!