Create 13a. string methods

Week 2: Methods, strings and lists/13a. string methods

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+// indexOf - starting idx of the 1st matching character of the substring
+String s = "An example";
+s.indexOf("xample") == 4;
+
+
+// contains 
+Examples of method usage:
+String start = "I am really starting to get into Java.";
+
+System.out.println(start.contains("really"));
+System.out.println(start.contains("java")); // written in lowercase
+
+System.out.println(start.indexOf("am"));
+System.out.println(start.indexOf("java"));
+ 
+
+Program outputs:
+true
+false
+2
+-1
+
+
+
+
+// replace
+String start = "I am really starting to get into Java.";
+String fixed = start.replace("Java", "C#");
+System.out.println(fixed);
+
+Program outputs:
+I am really starting to get into C#.
+
+
+
+// NO IN-PLACE REPLACEMENT OF SUBSTRING
+A typical mistake when using the replace method is to forget that the method DOES NOT MODIFY the original string.
+For example, the following code will not return an error
+
+String nephews = "Huey, Dewey and Rouie";
+nephews.replace("Rouie", "Louie");
+System.out.println(nephews);
+ 
+Program outputs:
+Huey, Dewey and Rouie
+
+
+VS
+
+// ASSIGNING BACK TO THE SAME VARIABLE
+String nephews = "Huey, Dewey and Rouie";
+nephews = nephews.replace("Rouie", "Louie");
+System.out.println(nephews);
+ 
+
+Program outputs:
+
+Huey, Dewey and Louie
+
+
+