CSC1401 Strings text

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CSC1401Strings (text)
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Learning Goals

• Working with Strings as a data type (a class)
• Input and output of Strings
• String operations

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Strings

• Anything within double quotes
• Examples
• System.out.println(Hi)
• System.out.println(The amount is money)
• String name Steve

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Strings as a Java class

• Note that we do not need an import statement
• Formally, we should write
• String name
• name new String (Steve)
• But its ok to write
• String name
• name Steve

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Input of Strings in Java (with Scanner)

• import java.util. // needed for scanner
• class IOTesting
• public static void main(String args)
• Scanner scan new Scanner(System.in)
• String course course scan.nextLine()

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Problem Solving with Strings

• We typically wish to
• Parse strings
• Change strings
• Java has lots of built-in String methods (check
  the Javadocs)
• Well just look at a few of them

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Entering your name

• import java.util. // needed for scanner
• class IOTesting
• public static void main(String args)
• Scanner scan new Scanner(System.in)
• String name name scan.nextLine()
• // if the person types in Steve Cooper
• // how can we get the first
• // and last names???

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What do we need to be able to do?

• Finding a string within a string (in this case a
  blank)
• indexOf (String searchString)
• indexOf (String searchString, int startPosition)
• Getting a part of a String
• substring (int start, int onecharafterend)
• substring (int start)

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In code

• System.out.println("Enter your name")String
  name sc.nextLine()
• int blank name.indexOf(" ")String first
  name.substring(0,blank)String last
  name.substring(blank1)System.out.println("Your
  first name is "
• first " and your last is " last)

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Another problem

• How many es are in your name?
• Two solutions
• Use indexOf (starting from the position after the
  last e was found)
• Use the charAt (int location) method
• Note that charAt returns a character, not a
  String. Characters may be tested for equality,
  , but not Strings

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Other string functions

• Assume that we have 2 string variables, first and
  last
• first.equals (last)
• Cannot use with Strings!
• first.replace (e, a)
• Replaces all es with as
• last.replaceFirst (o, ww)
• Replaces the first o with ww

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One last problem

• Determining if a string is an anagram
• How can we solve this?

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Summary

• Strings are how text gets represented in Java
• String is a built-in class, with lots of methods
  associated with it.

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Reading Assignment

• Media Computation, Chapter 12, Section 2, and pp
  435-437