What will be the output of this code:

int index = str.indexOf("o");

System.out.println(index);

What will be the output of this code?

String str = "Hello, World!";

String substring = str.substring(7);

System.out.println(substring);

What will be the output of this code:

String str = "OpenAI";

char ch = str.charAt(2);

System.out.println(ch);

What will be the output of this code:

String str = "Hello, World!";

String upperCase = str.toUpperCase();

System.out.println(upperCase);

What will be the output of this code:

String str = "Hello, World!";

System.out.println(str.length());

What will be the output of this code:

String str = "Java Programming";

System.out.println(str.substring(5, 12));