1. Switch, Strings, and ArrayLists in Java
CS102
Written by Robert Carver
Edited by Dean Zeller

2. Switch vs Else-If Statements
These are equivalent statements:

3. Switch General Form: switch(variable) case (value): (statements) break
A switch statement includes cases based on the value of a specific variable.
Each case is assigned to a different value and has statements it will execute as well as a break command.
In most switch statements there is a default case that executes if none of the other cases execute.
switch(variable)
case (value):
(statements)
break
default:

4. Strings – defining, +, length
Defining Strings:
A String variable is defined as String (name).
The string does not need content upon being defined.
String concatenation:
String objects can be concatenated to form other String objects.
String string3 = string1 + string 2;
String length:
string3.length() returns the amount of characters in string3 as an int value.

5. Strings – Escape Characters
Common Escape Characters: \b
Inserts a backspace \t
Inserts a horizontal tab \n
Inserts a newline \f
Inserts a form \r
Inserts a carriage return \”
Inserts a double quote (“) \’
Inserts a single quote (‘) \\
Inserts a backslash (\)
Escape characters are symbols that we cannot normally type into a string because of formatting reasons.

6. Strings – charAt, compareTo
charAt method:
Returns a character at the supplied string index.
Format: string.charAt(i)
compareTo method:
Compares strings based on the Unicode value of each character of the string, and returns a value.
if s1 > s2, it returns a positive number  
if s1 < s2, it returns a negative number  
if s1 == s2, it returns 0  
Format: s1.compareTo(s2)

7. Strings – concat and equals
concat method:
The concat method concatenates two strings together.
Format: string1 = string1.concat(string2)
equals method:
The equals method compares two strings and returns a Boolean value.
Is case sensitive, equalsIgnoreCase is not.
Format: Boolean value = string1.equals(string2)

8. Strings – indexOf, toUpper, toLower
indexOf method:
Returns the index of the first occurrence of a character in a string as an int. Format: string.indexOf(char)
lastIndexOf method:
Returns the index of the last occurrence of a character in a string as an int. Format: string.lastIndexOf(char)
toUpper and toLower methods:
Changes the characters of a string to upper or lower case
Format: string.toUpperCase(), string.toLowerCase()

9. Strings – replace and subString
replace method:
Replaces the selected chars, or char sequence, in a string with another char or char sequence.
Format: string.replace(char1,char2)
subString method:
Selects chars past a give index and returns the new substring.
Format: string.substring(index)
Creates a new substring selection in the given range.
Format: string.substring(index1, index2)

10. Strings – trim trim method
The trim method removes any trailing or leading whitespaces from a string.
Format: string.trim()

11. ArrayList – defining, get, and set
See example file for implementations of these methods with arrays.
Declaration: List<type> name = new ArrayList<type>()
Item retrieval: name.get(index) , returns item from supplied index.
Item reassignment: name.set(index, content), assigns item at index to new content.

12. ArrayList – remove, size, contains
See example file for implementations of these methods with arrays.
Item removal: name.remove(index), removes item at supplied index.
List Size: name.size(), returns int value of size of list.
Contains method: name.contains(search), searches the list for the supplied item and returns a Boolean value.

13. ArrayList – indexOf, isEmpty
See example file for implementations of these methods with arrays.
indexOf: name.indexOf(search), searches the list for the supplied item and returns the index of the item as an int.
isEmpty: name.isEmpty(), determines if list contains any elements. Returns a Boolean value.

14. Credits Content and visual organization by Robert Carver
Concept and final editing by Dean Zeller
Reference: Java An Introduction to Problem Solving, (8th edition) by Walter Savitch