how to display number values

this tutorial shows how to display number values and presents a simple programming task to complete

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program requirements

code a simple program to output values like 123 and 12.3

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learning-point

code

a number value like 123456 does not need speech marks when used in code

neither does a number like 123.456

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introducing the code

here is the new code that will be featured

1 System.out.println(123456);2 System.out.println(123.456);

understanding the code

on line 1 the println command is used again but this time using a number

notice the number is placed within the brackets but there are no speech marks

this number is a whole number, there is no fraction or decimal part

on line 2 the println command is used again, this time using a number containing a decimal point

this number is a real number, there is a fraction or decimal part

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The code above will produce this output in the console

123456123.456

The values are displayed as expected.

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worth knowing about displaying numbers

Be careful with numbers and with speech marks, otherwise you may get unexpected results! Here are some examples with explanations.

1 System.out.println(123);2 System.out.println("123");3 System.out.println(0123);4 System.out.println("0123");5 System.out.println(1+1);6 System.out.println("1+1");7 System.out.println("1" + "1");

would output ..

12312383012321+111

.. because

as we now know this is the way to display the number 123, one hundred and twenty three

this looks the same but it is the text 123

What! Well in java a leading 0 means that the remaining digits (123) are in

octal number base⁠

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This code displays the text 0123 (useful for phone numbers)

Since there are no speech marks, java calculates the result value of the arithmetic expression

There are speech marks and so java displays exactly the text within.

How come? Well in this case there are two “1” text characters joined (concatenated) together to give the text value 11. Not the number eleven. More about concatenation later.

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develop the code

Now that we have been introduced to println, let’s go on to prepare and run some code! There are some notes to read below before you open the project in

repl.it⁠

read the user interface design below to get an idea of what the program will produce.

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