AP Exam Study Cheat Sheet/Notes

Study Guide

Method

• 8 FRQ/1 Full Practice Exam/week
• No help allowed (no docs, no reference sheet, no compiler)
• Unlimited time to solve
• Self-score after doing FRQ/exam
• External research/compiler for testing allowed after self-scoring

Testing Resources (8 FRQ or 1 Practice Exam/Week)

CB Assigned FRQs & MCs CB Past FRQs

CB Topics Cheat Sheet

Key Sites

Geeks for Geeks

W3 Schools

Topic Summary

Primitive Types

• Java has 8 primitive types: int, double, boolean, char, byte, short, long, float.
• Variables store simple values, e.g., int x = 5; or double price = 3.99;.
• int for whole numbers, double for decimals, boolean for true/false.

Objects

• Classes define object types, and objects are instances of those classes.
• Use new keyword to create objects: String s = new String("hello");.
• Call methods with dot notation: s.length() or Math.abs(-4).

Boolean Expressions and if Statements

• Booleans: true, false; operators: &&, ||, !.
• Conditional statements:

  if (x > 5) {
      // do something
  } else {
      // do something else
  }
  

• Use equals() to compare strings: str1.equals(str2).

Iteration

• for, while, and do-while loops repeat blocks of code.
• Common use: traversing arrays or ArrayLists.

  for (int i = 0; i < arr.length; i++) {
      // loop body
  }
  

Writing Classes

• A class includes fields, constructors, and methods.

  public class Dog {
      private String name;
      public Dog(String n) { name = n; }
      public String getName() { return name; }
  }
  

Array

• Fixed-size containers: int[] nums = new int[5];.
• Use nums.length and index access: nums[0] = 1;.

ArrayList

• Resizable array:

  ArrayList<String> list = new ArrayList<>();
  list.add("hello");
  list.get(0);
  

• Requires import java.util.ArrayList;.

2D Array

• Arrays of arrays:

  int[][] grid = new int[3][4];
  grid[0][1] = 5;
  

• Access with grid[row][col]; use nested loops to iterate.

Inheritance

• A subclass inherits from a superclass using extends.

  public class Dog extends Animal {
      // subclass code
  }
  

• Use super() to call superclass constructors or methods.

Recursion

• A method that calls itself.
• Must include a base case and a recursive case.

  public int factorial(int n) {
      if (n == 0) return 1;
      return n * factorial(n - 1);
  }
  

MCQ

FRQ

2014: Problem 1 Work Revised

(Coded in REPL, includes test case)

public class Main {
  public static void main(String[] args) {
    recombine("john", "mort");
    String[] words = {"apple", "pear", "this", "cat", "doge", "fish", "blat", "pent"};
    mixedWords(words);
  }
  public static String recombine(String word1, String word2) {
    String finalString = "";
    String[] words = {word1, word2};
    for(int i = 0; i < words.length; i++) {
      if(i == 1) {
        for(int j = words[i].length()/2; j < words[i].length(); j++) {
          finalString += words[i].charAt(j);
        }
      }
      else {
        for(int j = 0; j < words[i].length()/2; j++) {
          finalString = finalString + words[i].charAt(j);
        }
      }
    }
    System.out.println(finalString);
    return finalString;
  }
  public static String[] mixedWords(String[] words) {
    String tempW = "";
    for(int i = 0; i < words.length; i+=2) { 
      tempW = recombine(words[i], words[i+1]);
      words[i+1] = recombine(words[i+1], words[i]);
      words[i] = tempW;
    }
    return words;
  }
}

Output

jort
apar
peple
that
cis
dosh
fige
blnt
peat