CSIS 110 - Lecture 18
Quiz:
Next Friday (October 14) - Primarily on arrays, ArrayLists, and Strings
Strings:
We looked at some String methods:
- length
- equals
- charAt( int index )
- indexOf( char c ), indexOf( char c, int startIndex )
- lastIndexOf( char c ), lastIndexOf( char c, int startIndex )
- substring( int startIndex, int lastIndex ), substring( int startIndex )
- toUpperCase(), toLowerCase()
Let's try some examples:
Count the number of 'A's in a String
Print every other character in a String
Print a String in reverse order
Random Numbers
Open BlueJ. Java contains a class Random – go look it up in the Java documentation.
(Help | Java Class Libraries ).
What package is it contained in? (That is, where do you need to tell Java to look for the
Random class in an import statement?)
How do you create an instance of a Random?
How do you generate a random number?
- create an instance of class Random
- call a method on that object to get a number
Open the RandomExample project (in chapter 5 directory). Go ahead and play around
with it.
What do the methods do?
What is the difference between the two versions of printTenRandoms?
Lab Exercise
See DNAStringLab.doc