AP Computer Science Java Vocabulary Review

Java Quick Reference

• Accessible Methods from the Java Library:

  • class java.lang.Object:

  • boolean equals (Object other)

  • String toString()

  • class java.lang.Integer:

  • Integer (int value)

  • int intValue()

  • Integer.MIN_VALUE

  • Integer.MAX_VALUE

  • class java.lang.Double:

  • Double (double value)

  • double doubleValue()

  • class java.lang.String:

  • int length()

  • String substring(int from, int to)

    • returns substring from 'from' to 'to-1'

  • String substring(int from)

    • returns substring from 'from' to end

  • int indexOf(String str)

    • returns the index of first occurrence of str, -1 if not found

  • int compareTo(String other)

    • returns < 0 if less than other, = 0 if equal, > 0 if greater

  • class java.lang.Math:

  • static int abs(int x)

  • static double abs(double x)

  • static double pow(double base, double exponent)

  • static double sqrt(double x)

  • static double random()

  • interface java.util.List:

  • int size()

  • boolean add(E obj)

    • append obj to end of list

  • void add(int index, E obj)

    • insert obj at position index, shifting elements

  • E get(int index)

  • E set(int index, E obj)

    • replace element at position index

  • E remove(int index)

    • remove element at position index

AP Computer Science Java Subset

• Purpose of the Java Subset

  • Outline features of Java that may appear on the AP Computer Science A Exam.

  • Supplementary details on input/output methods are not tested.

• Key Features in the AP Java Subset:

  • Enables meaningful question formulation.

  • Assists students in test preparation.

  • Allows instructor flexibility in teaching methods.

Language Features on AP CS A Exam

• Tested Language Features:

  • Comments: /* */, //, /** ... */

  • Primitive Types: int, char, boolean, etc.

  • Operators: Arithmetic (+, -), Increment/Decrement (++, --), Assignment (=), Etc.

  • Control Statements: if, else, while, for, return

  • Variables: Include parameter and local variables

• Not Tested Features:

  • User input methods (Scanner, System.in, etc.)

  • 3D arrays and other complex arrays

  • switch statements, try/catch/finally

Working with Arrays

• Array Characteristics:

  • All items in an array must be of the same data type.

  • Length can be found using nameOfArray.length.

• 1D Arrays:

  • Declaration: int[] example = new int[10];

  • Initialization: int[] example2 = {1, 2, 5, 6};

  • Printing: Arrays.toString(example2);

• 2D Arrays:

  • Declaration: int[][] example3 = new int[3][4];

  • Row-major order indexing.

• Searching Arrays:

  • Sequential Search: Check each element until key is found.

  • Binary Search: Requires sorted array.

Exception Handling

• Exceptions to Watch:

  • NullPointerException

  • IndexOutOfBoundsException

  • ArithmeticException

  • IllegalArgumentException

• Handling Exceptions:

  • try / catch blocks used for observing code that could throw exceptions.

Javadoc Comments

• Purpose: Generates HTML documentation from code comments.

• Common Tags:

  • @param, @return, @exception, @author

  • Usage Example: ```java /**

    • Method description

    • @param arg1 description

    • @return description
      */
      public void method(int arg1){}
      ```

Test-Taking Tips for AP Computer Science Exam

• Multiple Choice Tips:

  • Read questions carefully; focus on keywords.

  • Use scratch paper for calculations.

  • Guess only if you can eliminate at least 2 options.

• Free Response Tips:

  • Read the whole question, then focus on parts incrementally.

  • Reuse code and methods wherever possible to avoid redundancy.

  • Time management is crucial; aim for 20 minutes per question.

Recursion

• Definition: Method calling itself with a base case.

  • Example: Factorial implementation.

Polymorphism and Inheritance

• Polymorphism: An object can take many forms, typically through class references.

• Inheritance: Allows a child class to inherit properties and behavior from a parent class.

• Example: class Child extends Parent {}