Output

A program's output is the information it sends to some external location, such as the terminal, the screen, a speaker, a file, or a web server. For now, our only method of producing output will be printing text to the terminal.

We will primarily use the println function, which you saw in the previous section. There is a similar function called print, which is slightly different. To illustrate the difference, here are two jshell scripts, abcPrintln.jsh and abcPrint.jsh, along with their output:

println("A");
println("B");
println("C");
/exit

print("A");
print("B");
print("C");
/exit

$ jshell --execution local abcPrintln.jsh
A
B
C
$ jshell --execution local abcPrint.jsh
ABC$

As you can see, the println function moves to the next line after printing. This is because it adds a line break to the end of whatever text it prints. The print function does not, which even leads to the terminal prompt ($) being on the same line as the second program's output!

Usually you'll want to use println, but print can be helpful if you want to create a line of output into multiple print statements.

Escape Sequences

If you've experimented with printing, then you may have noticed that you cannot print a double-quote ("). This is because double-quotes are used to mark the beginning and end of a string of text. You can print " and a number of other special characters using escape sequences. These are typically a backslash (\) followed by the character or a letter standing in for the special symbol you want to include:

  • \" is printed as "
  • \\ is printed as \
  • \t is printed as a tab
  • \n is printed as a line break

Try printing messages containing these escape sequences and see what happens!