From my textbook:

When you write a floating-point literal in your program code, Java assumes it to be of the double data type. A double value is not compatible with a float variable because a double can be much larger or smaller than the allowable range for a float. As a result, code such as the following will cause an error:

Example 1:

float number;
number = 23.5;       //Error!

You can force a double to be treated as a float, by suffixing it with the letter F or f. The preceding code can be rewritten in the following manner to prevent an error:

Example 2:

float number;
number = 23.5F;       //This will work.

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I can't figure out why example 1 produces an error. Why is 23.5 considered a double? I thought it was a float.

AFAIK, float numbers are precise up to 7 decimal digits of accuracy. 23.5 only has 1 decimal digit. What am I not understanding? I thought by typing 'float number;' you are declaring the number variable to be a float. Why would you need the extra step of adding an F?

Thanks