Making Java Speak: Understanding Output
So far, we’ve explored the basic syntax, variables and data types. In this blog we’ll see how and where Java displays information to us with a few fun exercises waiting for you at the end.
What is output?
Output is the information displayed by a program, either in a terminal, a browser, or another interface.
In the example below, I’m printing the output(result) in my terminal. If you’re wondering what a terminal is, then consider it like your notebook but only text based. For me it is the playground where I experiment with and test my code.
Now, let’s decode each keyword in line 5, for the remaining code we’ve covered in the previous blog.
- System — A built-in Java class that provides access to standard input, output and error streams.
- out — The standard output stream used to display information on the screen.
- println() — A method that prints whatever is inside the parentheses and then moves the cursor to the next line (ln is new line).
Let’s take a look at the example above, (‘a’) represents a character hence the single quotes. (“Learning Java …”) is a string hence the double quotes. Now look carefully (“I ate 2 apples”) here 2 is an integer but since it is within the double quotes it gets represented as a string and lastly (2) has no quotes since we want it to be printed as integer.
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You might be wondering why not represent the integer 2 within the quotes like a string, apart from the memory allocation what else matters here. Well there is more to it, let’s take a look at the example below:
One might wonder how (2 + 2) returns 4 and (“2” + “2”) returns 22 and not 4 or 2 2, this concept is called Concatenation. The + operator behaves differently depending on the data type involved. When used with numbers, it performs addition. When used with strings, it joins them together.You can think of it as a glue that sticks pieces of text together.
Let’s practice this concept, what would be the output of
String name = "Mickey";
System.out.print(name + " Mouse");Now, we’ll see what’s the difference between print() and println(). print() will print the output on the same line whereas, println() will print the output on a new line.
Exercises:
What is the output of the following:
int age = 18;
System.out.println("The eligible age to cast a vote is " + age);System.out.println(5 + 5);
System.out.println("5" + 5);
System.out.println("5" + "5");System.out.print("Hello ");
System.out.print("World");Don’t run the code just yet. Try predicting the output first and then verify your answers by running the program. Programming becomes much more fun when you guess before you execute.
