Value is getting multiply by 100 when using percentage on value axis bar chart JfreeChart

Question

I am using JfreeChart 1.0.15 library.
I want to show percentage score of the college and branches, so I used setNumberFormatOverride() method

final NumberAxis valueAxis = new NumberAxis("Percentage Score");
valueAxis.setNumberFormatOverride(NumberFormat.getPercentInstance());

It is showing me the % sign on the Y-axis but all the values are getting multiplied by 100.

Actual output

See the Y-axis values. Label values on the bars are correct.

If I divide each value by 100 then Y-axis values are correct (e.g. 15%,19%,25%,27%) but label values are displaying wrong (e.g. 0.15,0.19,0.25,0.27).

Below code also won't give the desired output

DecimalFormat pctFormat = new DecimalFormat("#.0%");
valueAxis.setNumberFormatOverride(pctFormat);

I tried different solutions from

none of them worked.
If you need more information let me know.

What format are your numbers in before? What do you mean by _label values are displaying wrong_? Can you give us some code? — Keppil, Jan 29 '14 at 06:32
@Keppil : `label values are displaying wrong` means 0.19, 0.27 etc where as on the Y-axis values are 19%,27% etc — Aniket Kulkarni, Jan 29 '14 at 06:37
Well, `0.19` is the same as `19%`, so it sounds like what you are trying to do is use the `%` in a non-standard way. — Keppil, Jan 29 '14 at 06:39
@Keppil : Yes. You are right, so how can I show the label values from 0.19 to 19%? — Aniket Kulkarni, Jan 29 '14 at 06:41

Mike B · Answer 1 · 2014-01-29T07:13:26.633

If you look at the source for NumberFormat you'll see that NumberFormat#getPercentInstance() actually returns a DecimalFormat instance. Although it's not immediately obvious from the source what format string that instance uses it's safe to assume it contains a %.

According to the DecimalFormat javadoc section titled Special Pattern Characters, a % in a format string means Multiply by 100 and show as percentage. Luckily NumberFormat provides a setMultiplier() method, so you can do this to fix your issue:

DecimalFormat pctFormat = new DecimalFormat("##.0%");
pctFormat.setMultiplier(1);
valueAxis.setNumberFormatOverride(pctFormat);

I believe you can also enquote the %, like this:

DecimalFormat pctFormat = new DecimalFormat("##.0'%'");
valueAxis.setNumberFormatOverride(pctFormat);

+1 and Thanks for Java docs reference. Now, this multiply by 100 problem solved. I also tried some from above Keppil comments. Another way is to set the label and the percentage format. — Aniket Kulkarni, Jan 29 '14 at 07:13

score 0 · Accepted Answer · edited May 23 '17 at 12:33

Thanks @Keppil. I managed to solve from your valuable comment

I was using below code to set label

barPlot.getRenderer().setBaseItemLabelGenerator(new StandardCategoryItemLabelGenerator());
barPlot.getRenderer().setBaseItemLabelsVisible(true);

The mistake was invoking default constructor StandardCategoryItemLabelGenerator().
See question labels are not in percent % format.

I solved by passing NumberFormat instance pctFormat to the parameterized constructor StandardCategoryItemLabelGenerator(java.lang.String labelFormat, java.text.NumberFormat formatter)

barPlot.getRenderer().setBaseItemLabelGenerator(new StandardCategoryItemLabelGenerator("{2}",pctFormat));
barPlot.getRenderer().setBaseItemLabelsVisible(true);

Correct output

Now format has been applied to the labels also.

Value is getting multiply by 100 when using percentage on value axis bar chart JfreeChart

2 Answers2