Format Printing
From Progzoo
Using Print Formatting
printf method provides a powerful and succinct mechanism for solving many formatting problems.
The printf method
The printf method takes a formatting string followed by any number of additional parameters. The formatting string includes a number of escape sequences - each of these is substituted by the actual parameter given.
%s is used when a string is expected %d is used when an integer (or long) is expected %f is used when a floating point number is expected
The result of
System.out.printf("The GDP of %s is %d.\n", name, gdp);
is
The GDP of United Kingdom is 1782000000000. The GDP of Uganda is 39390000000.
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Using printf to align
We can format output involving fixed and variable components. Usually we align strings to the left and numbers to the right.
Country: United Kingdom GDP: 1,782,000,000,000 Country: Uganda GDP: 39,390,000,000
In the printf a number of values may follow the format string.
These values are used up by % placeholders in the format string.
"Country: %-18s GDP: %,20d\n"
%-18s- the minus in
-18means align left,
- the minus in
the 18 means 18 characters
are to be used, the s is for string.
%,20d- the comma means include , separator every three digits, the 20 means use 20 characters and align right, d is for decimal.
%9.2f- f is for floating point; it will use 9 spaces altogether including 2 decimal places
\n- This starts a new line.
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