html - Need help creating a drop down button with Java -

html - Need help creating a drop down button with Java -

i new programming in java. trying create button when clicked produce drop down. example, have user input field google type rolling search , separate button when clicked display window right of brings available options.

here button:

<input id = "maincontainer" type = "button" value = " + ";>

is there way create drop downwards menu after clicking button html or css? or need in javascript?

it not seem hard theoretically not know much java don't have much of starting point. believe need onclick() event create new menu. don't know how write out in java. need finish project in next 2 weeks help appreciated.

if provide code explanation of how works happiest dude in world. reference appreciated.

you can write own using javascript or utilize ui components such as: jquery autocomplete

java html select button drop-down-menu