1. CS240: Advanced Programming Concepts
Week 2
Thursday

2. Topics Final values Wrapper classes and Autoboxing Arguments
More on Arrays
“==“ vs “.equals()”
Lab 2 walkthrough

3. “Final” Values
Set once then immutable…

4. Primitive Data Types and Wrapper Classes
Sometimes you just need an object…
Enter wrapper classes for primitive data types
Autoboxing and unboxing allows us to “ignore” the wrapper and treat the variable like a primitive (i.e. static declarations/allocations)

5. Argument Passing Pass by value… Arrays as arguments and return types…
Primitives
References
Arrays as arguments and return types…

6. More on Arrays Arrays as arguments and return types… Arrays of
References
Primitives
Can I truly have an array of objects? – no not really, I’ll get an array of references that must be associated with individually allocated objects, the memory is dynamically allocated on the heap so I don’t really know if it is contiguous.

7. “==“ vs “.equals()”
“==“ looks at the value of the variables. What does this mean for
primitives?
references?
.equals()
Tests an “equivalence relation”
Related to hashCode()

8. Lab 2 Read/Walk Through (To be continued)
Trie data structure
Characters as indexes
Use a char
Use a hashmap
Methods to override…
Equals method() – review hashCode…
Similarity of words
Cumulative edit distance <= 2
Four edit distances
Deletion
Transposition (adjacent)
Alteration
Insertion