Java Video Tutorial 13

Java Video Tutorial 13In 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";
			System.out.println("They're equal");
			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()
		// contains() returns a boolean depending on whether the 
		// String contains the String you pass it
		// endsWith() checks if the String ends with the String you pass
		// startsWith() works similar to endsWith()
		// indexOf() returns the 1st index that matches the String passed
		// 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 
		// toCharArray() inserts every character in the string into
		// separate indexes in an array 
		char[] charArray = letters.toCharArray();
		// substring() returns a String starting at the first index
		// through the last index provided
		// toUpperCase() converts all letters into uppercase
		// toLowerCase() does the opposite
		String randString = "   abc   ";
		// trim() gets rid of leading and trailing white space
		// 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
		// 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
		// ensureCapacity() increases the capacity for the SB
		// length() returns the number of characters in the SB
		// trimToSize() forces capacity to equal length
		// 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()

10 Responses to “Java Video Tutorial 13”

  1. Anonymous says:

    Thanks for the video ,u r doing a great job Derek.

  2. Aamir says:

    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.

  3. Nirjhar says:

    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

  4. Yoav says:

    Your videos are amaizing,
    Thanks Thanks Thanks.

  5. saquib says:

    Derek, aah!! what to say about you. keep it up!! you are just fabulous, MashaALLAH.

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