Bonita High School
AP Computer Science A | Java Quick Reference
AP Java subset review

Know what the quick reference gives you.

The AP exam gives you this reference sheet, but it does not explain when or why to use each method. Use this page to connect signatures, return values, indexing rules, and common AP-style traps.

Explore methods Practice Official PDF
Interactive Reference

Search, filter, and study the Java subset

Filter by class, search for a method, then open a card to see its purpose, example, and AP exam reminder.

Practice Mode

Predict before you reveal

These quick checks focus on the patterns students most often miss: end-exclusive substrings, `indexOf` returning `-1`, `ArrayList` shifting, `random` ranges, and scanner line-reading behavior.

String

Practice prompt


            

              
              
            

          

          
        

      

    


    

      

        
How to Study

        
Turn the reference sheet into memory

        

          

            
1. Name the return type

            
Before using a method, say what it returns. `length()` returns an `int`; `substring` returns a `String`; `set` returns the old element.

          

          

            
2. Trace the indices

            
Write positions above a string or list. Most AP mistakes happen when students skip the index map.

          

          

            
3. Explain the side effect

            
Ask whether the method changes the object. `ArrayList add`, `set`, and `remove` change the list; `String` methods return new values.

          

        

        

          
Official Source

          
This page is a study companion for the College Board AP Computer Science A Java Quick Reference. Use the official PDF as the final authority for exam-day wording and included methods.