What do the following functions return?

String x = "Vision";
String y = "2020";
System.out.println(x.charAt(3));

Predict the output of the following Java program snippet:

String S1 = "Computer World";
String S2 = "COMPUTER WORLD";
String S3 = "Computer world";
String S4 = "computer world";
System.out.println(S1 + " equals "+ S2 + " " + S1.equals(S2)); 
System.out.println(S1 + " equals "+ S3 + " " + S1.equals(S3)); 
System.out.println(S1 + " equals "+ S4 + " " + S1.equals(S4)); 
System.out.println(S1 + " equalsIgnoreCase "+ S4 + " " + S1.equalsIgnoreCase(S4));

What do the following functions return?

String x = "Vision";
String y = "2020";
System.out.println(x.length());

If:
String x = "Computer";
String y = "Applications";

What do the following function returns?

System.out.println(x.substring(1,5));