Double instance variables in java

Question

Why do double instance variables in java have a lower case d attached to them? Do they need to have this?

Example:

double area = 0d;
double avgDailyTemp = 26d;

etc...

See this answer: stackoverflow.com/a/28353219/1057429 it talks about long but provides information about double as well — Nir Alfasi
– Nir Alfasi, Commented Feb 7, 2015 at 22:20
Can you reword your question, because its unclear. whats a double instance variable? double is primitive and not an object, primitives are lower cased in Java — Sleiman Jneidi
– Sleiman Jneidi, Commented Feb 7, 2015 at 22:22
@SleimanJneidi OP is asking if d part in 26d is mandatory for double. — Pshemo
– Pshemo, Commented Feb 7, 2015 at 22:30

Alex Popov · Accepted Answer · 2015-02-07 22:23:33Z

4

A number literal by default is an integer. If you attempt to pass a number like ten billion into Java double it'll error since it's outside the bounds of an integer. Specifying the lowercase d explicitly defines it as a double literal instead.

answered Feb 7, 2015 at 22:23

Alex Popov

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1 Comment

OlgaMaciaszek Over a year ago

You can also add a "." at the end instead of d: double area = 260000000000.;

MariuszS · Accepted Answer · 2015-02-07 22:45:57Z

1

double a = 10000000000; // ERROR! Integer number too large 
double b = 10000000000d; // OK!

answered Feb 7, 2015 at 22:45

MariuszS

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Michael Welch · Accepted Answer · 2015-02-07 22:20:25Z

0

Without the d the numbers 0 and 26 are int values.

answered Feb 7, 2015 at 22:20

Michael Welch

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Brett Okken · Accepted Answer · 2015-02-07 22:21:23Z

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It is not the variable which requires the d, but the constant value declared. It is a "hint" to the compiler of the data type.

http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html

answered Feb 7, 2015 at 22:21

Brett Okken

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