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Parsing string values

From: Java Essential Training

Video: Parsing string values

The string class has many methods that you can use to manipulate and parse its values; I'll show you some of these methods in this project, Parsing Strings. I'm starting in an empty main method and I'll declare a variable named s1 with a value of "Welcome to California!" First, I'll show you how to find out how long a string is. I use System.out.println and I'll output "Length of string:" and then to find out how long the string is, use the length method, s1.length.

Parsing string values

The string class has many methods that you can use to manipulate and parse its values; I'll show you some of these methods in this project, Parsing Strings. I'm starting in an empty main method and I'll declare a variable named s1 with a value of "Welcome to California!" First, I'll show you how to find out how long a string is. I use System.out.println and I'll output "Length of string:" and then to find out how long the string is, use the length method, s1.length.

I'll run the application and there's the result. You can also parse strings using methods of the string class. Here, I'm going to show you how to find a string within a string, I'll declare an integer variable named pos for position, and I'll call the method s1.IndexOf. You'll see when I press Ctrl+Space that there are a number of versions of the IndexOf method; you can parse in a character or string starting from a particular location. I'm going to use the version that's looks for a particular strength, and I'll pass in a literal string of ("California ") and then I'll output the value of the position character using (" Position of California":) and then I'll append pos.

I'll run the application and it tells me that California starts at position 11. Next, I'll show you how to extract a value from a particular position of the string. I'll declare a new string called sub, and I'll call s1.substring. The substring method has three different versions, the one that passes in a single integer, the one that takes a single integer and an ending integer, and one called subsequence, named differently, that returns a character sequence. I'm going to use the substring method and I'll ask for the value starting at position 11, then I'll use System.out .println again, and I'll output the substring that I extracted.

I'll Run the application and there is a result, I get everything starting at the word California! including the exclamation mark at the end. Finally, I'll show you how to trim a string that might have spaces at the end. I'll create a new string called s2 and I'll give it a value of "Welcome!" and I'm going to add a whole bunch spaces at the end of the string. Then I'll declare an int variable named len1, and get its value from s2.length, and I'll output the value of len1.

I'll Run the application and I get a value of 15. Then I'll declare another variable named s3, and I'll get its value from s2.trim, the trim method removes the extra white space. Then I'll make a copy of my print line command and this time I use a slightly more extended syntax, so I don't have to create another integer variable. It will look like this, s3.length. I'll Save my might changes and Run the application and after trimming, I'm down to just eight characters. In this exercise I've shown you some of what I think are the most useful members of the string class, but again, I encourage you to look at the documentation for the string class.

You'll find in this list of methods many, many tools that you can use to extract, manipulate, convert and otherwise use the string class however you need to in your applications.

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This video is part of

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Java Essential Training

71 video lessons · 69603 viewers

David Gassner
Author

 
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  1. 10m 8s
    1. Welcome
      1m 3s
    2. Is this course for you?
      5m 35s
    3. Using the exercise files
      3m 30s
  2. 31m 24s
    1. The history of Java
      5m 19s
    2. Java compilation and syntax
      8m 54s
    3. Understanding the principles of Java
      8m 28s
    4. Choosing a development environment
      8m 43s
  3. 19m 5s
    1. Installing Java on Windows
      6m 42s
    2. Installing Eclipse on Windows
      3m 19s
    3. Exploring Java on Mac OS X Leopard and Snow Leopard
      2m 27s
    4. Installing Java on Mac OS X Lion
      3m 27s
    5. Installing Eclipse on Mac OS X
      3m 10s
  4. 46m 10s
    1. Creating a Hello World application
      11m 7s
    2. Exploring the Eclipse IDE
      8m 55s
    3. Compiling and running from the command line
      8m 2s
    4. Passing arguments to the application
      8m 17s
    5. Using the Java API documentation
      4m 5s
    6. Memory management and garbage collection
      5m 44s
  5. 58m 57s
    1. Everything is an object
      5m 59s
    2. Declaring and initializing variables
      9m 15s
    3. Working with numbers
      8m 32s
    4. Converting numeric values
      6m 40s
    5. Understanding operators
      7m 58s
    6. Working with character values
      5m 14s
    7. Working with boolean values
      5m 13s
    8. Outputting primitive values as strings
      5m 33s
    9. Creating a simple calculator application
      4m 33s
  6. 53m 40s
    1. Writing conditional code
      5m 35s
    2. Using the switch statement
      8m 50s
    3. Repeating code blocks with loops
      7m 35s
    4. Creating reusable code with methods
      6m 31s
    5. Declaring methods with arguments
      5m 41s
    6. Overloading method names with different signatures
      5m 53s
    7. Passing arguments by reference or by value
      5m 35s
    8. Creating a more complex calculator application
      8m 0s
  7. 20m 30s
    1. Using the String class
      5m 44s
    2. Building strings with StringBuilder
      3m 34s
    3. Parsing string values
      3m 19s
    4. Working with date values
      7m 53s
  8. 20m 44s
    1. Understanding compile-time vs. runtime errors
      4m 5s
    2. Handling exceptions with try/catch
      4m 55s
    3. Throwing exceptions in methods
      2m 50s
    4. Using the debugger
      8m 54s
  9. 32m 22s
    1. Using simple arrays
      4m 47s
    2. Using two-dimensional arrays
      6m 17s
    3. Managing resizable arrays with ArrayList
      7m 14s
    4. Managing unordered data with HashMap
      6m 5s
    5. Looping through collections with iterators
      7m 59s
  10. 52m 2s
    1. Understanding encapsulation
      5m 59s
    2. Creating and instantiating custom classes
      8m 8s
    3. Organizing classes with packages
      6m 47s
    4. Creating and using instance methods
      6m 52s
    5. Storing data in instance variables
      6m 56s
    6. Using constructor methods
      5m 40s
    7. Managing instance data with getter and setter methods
      8m 26s
    8. Using class variables and Enum classes
      3m 14s
  11. 41m 15s
    1. Understanding inheritance and polymorphism
      9m 12s
    2. Extending custom classes
      9m 1s
    3. Overriding superclass methods
      3m 8s
    4. Casting subclass objects
      5m 3s
    5. Understanding interfaces and implementing classes
      4m 2s
    6. Creating your own interfaces
      4m 14s
    7. Using abstract classes and methods
      6m 35s
  12. 32m 17s
    1. Managing files with the core class library
      7m 46s
    2. Managing files with Apache Commons FileUtils
      7m 32s
    3. Reading a text file from a networked resource
      7m 52s
    4. Parsing an XML file with DOM
      9m 7s
  13. 17m 39s
    1. Creating your own JAR files
      4m 54s
    2. Understanding the classpath
      5m 2s
    3. Documenting code with Javadoc
      7m 43s
  14. 47s
    1. Goodbye
      47s

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