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Just start with the loop.
Then add the other stuff one thing at a time.

There are hundreds of pieces of code on this forum and thousands on the internet.
Search here or Google for samples.
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Time to use the compiler and see what it thinks.

Not quite.
You should use the length of the String to control the number of loops. Don't hard code a 4.
You've mixed the data type and the variable name: char aChar = 0; char < 4; char++
char is a...

You do it pretty much just like you asked:
write a loop -> See for() loop for example
in the loop get the char from the String one by one -> Read the String class API doc for the method

Ok. Normally I think of "display" as something that a human can see. Putting a value in an array is differeent than displaying it.
You "display" a String by using System.out.println to a console or...

Have you read the String class API documentation? The String class has methods to get at the individual characters in the String. You could write a loop to iterate over the String and get the char...