Java Video Tutorial 13
In this part of the Java Video Tutorial I cover most every method available for manipulating Strings and StringBuilders.
This is one of the last simple Java Tutorial videos. Everything after this will cover advanced topics.
All of the code follows the video. It is very heavily commented. If you print it out it will help you better retain this information.
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Code from the Video
// Here I introduce the String class
// A String is an object unlike the other primitive data types
import java.util.Arrays;
public class LessonThirteen {
public static void main(String[] args){
// You create a String like this
String randomString = "I'm just a random string";
// If you want to use quotes in a string escape it with \
// Always surround Strings with quotes " " and not Apostrophes ' '
String gotToQuote ="He said, \"I'm here\"";
/* Other common Escape Codes
* \n : Newline
* \b : Backspace
* \' : Apostrophe
* \" : Quote
* \\ : Backslash
*/
// You combine Strings with a +
System.out.println(randomString + " " + gotToQuote);
// You can add other data type to the string with a +
int numTwo = 2;
System.out.println(randomString + " " + numTwo);
/* You convert primitive types to a string with toString
* String byteString = Byte.toString(bigByte);
* String shortString = Short.toString(bigByte);
* String intString = Integer.toString(bigInt);
* String longString = Long.toString(bigByte);
* String floatString = Float.toString(bigByte);
* String doubleString = Double.toString(bigByte);
* String booleanString = Boolean.toString(bigByte);
*
* You convert from String to primitives with parse
* int stringToInt = Integer.parseInt(intString);
* parseSort, parseLong, parseByte, parseDouble,
* parseBoolean, parseFloat
*/
// You compare strings with equals or equalsIgnoreCase
String uppercaseStr = "BIG";
String lowercaseStr = "big";
if(uppercaseStr.equals(lowercaseStr))
{
System.out.println("They're equal");
}
if(uppercaseStr.equalsIgnoreCase(lowercaseStr))
{
System.out.println("Same letters");
}
String letters = "abcde";
String moreLetters = "fghijk";
// charAt returns the character in a string
System.out.println("2nd Character: " + letters.charAt(1));
// compareTo returns 0 if strings are equal
// Returns a negative number if letters comes before moreLetters
// Returns a positive number if letters comes after moreLetters
// There is also a compareToIgnoreCase()
System.out.println(letters.compareTo(moreLetters));
// contains() returns a boolean depending on whether the
// String contains the String you pass it
System.out.println(letters.contains("abc"));
// endsWith() checks if the String ends with the String you pass
System.out.println(letters.endsWith("de"));
// startsWith() works similar to endsWith()
// indexOf() returns the 1st index that matches the String passed
System.out.println(letters.indexOf("cd"));
// You can also specify the index to start searching from
// indexOf(StringToLookFor, IndexStartPosition)
// lastIndexOf() works like indexOf except it starts from the
// end of the String you are searching
// length() returns the number of characters in a String
System.out.println("Length of string: " + letters.length());
// replace() replaces every occurrence of the first String with
// the second String you provide
System.out.println(letters.replace("abc", "xy"));
// You can create an array of Strings with split()
// You define how to break up the String using a delimiter
// If you had 123,456 and used the delimiter "," you would
// create the array [123,456]
String[] letterArray = letters.split("");
// toString() converts the array into a String to print it
System.out.println(Arrays.toString(letterArray));
// toCharArray() inserts every character in the string into
// separate indexes in an array
char[] charArray = letters.toCharArray();
System.out.println(Arrays.toString(charArray));
// substring() returns a String starting at the first index
// through the last index provided
System.out.println(letters.substring(1,4));
// toUpperCase() converts all letters into uppercase
// toLowerCase() does the opposite
System.out.println(letters.toUpperCase());
String randString = " abc ";
// trim() gets rid of leading and trailing white space
System.out.println(randString.trim());
// A String is immutable, which means every time you change
// a String a new version is created in memory.
// If you manipulate Strings allot use a StringBuilder
// How to create a StringBuilder
// It has a fixed space in memory
StringBuilder randSB = new StringBuilder("A random string");
// append() adds anything to the end of a SB
System.out.println(randSB.append(" again"));
// append() permanently effected the StringBuilder
System.out.println(randSB);
// delete() removes part of the SB from first index to the last
System.out.println(randSB.delete(15, 21));
// deleteCharAt(index) is used to delete individual chars
// capacity() returns the number of indexs for the SB
System.out.println(randSB.capacity());
// ensureCapacity() increases the capacity for the SB
randSB.ensureCapacity(60);
System.out.println(randSB.capacity());
// length() returns the number of characters in the SB
System.out.println(randSB.length());
// trimToSize() forces capacity to equal length
randSB.trimToSize();
// insert() inserts at the index you provide anything
System.out.println(randSB.insert(1, "nother"));
// toString converts a SB into a String
String oldSB = randSB.toString();
/* StringBuilders also have the same methods as Strings
* charAt(), indexOf(), lastIndexOf(), subString()
*/
}
}
Thanks for the video ,u r doing a great job Derek.
Thank you 🙂
Derek thanks for video, u said in one of the reply to my comment that Java combined with c can do anything,is it really possible, i mean Can Java & C be combined to form Softwares, if so how?,Plz do respond.
There are many ways and Ill cover this topic soon. Here is a nice article that will get you going now http://www.nag.com/IndustryArticles/CallingCLibraryRoutinesfromJava.pdf
Hi,
I really like your website.
1. Can you post a video on how to parse a text file using Java.
2. Video to parse JSON using java or javascript
3. Video to parse or download images using java from website
Have you seen this tutorial Parse XML with Java. I have a bunch of videos on that topic that follow this one as well. I hope that helps
Your videos are amaizing,
Thanks Thanks Thanks.
Thank you very much 🙂 I’m happy that you are enjoying them.
Derek, aah!! what to say about you. keep it up!! you are just fabulous, MashaALLAH.
Insha’Allah! Thank you for your kind message 🙂