# Manage Chart Data Labels in Presentations Using Java

> Learn to add and format chart data labels in PowerPoint presentations using Aspose.Slides for Java for more engaging slides.

Source: https://docs.aspose.com/slides/java/chart-data-label/
Updated: 2026-08-05


## **Introduction**

Data labels on a chart show details about the chart data series or individual data points. They allow readers to quickly identify data series and they also make charts easier to understand.

## **Set Data Precision in Chart Data Labels**

This Java code shows you how to set the data precision in a chart data label:

```java
import com.aspose.slides.*;

Presentation pres = new Presentation();
try {
    IChart chart = pres.getSlides().get_Item(0).getShapes().addChart(ChartType.Line, 50, 50, 450, 300);
    
    chart.setDataTable(true);
    chart.getChartData().getSeries().get_Item(0).setNumberFormatOfValues("#,##0.00");

    pres.save("output.pptx",SaveFormat.Pptx);
} finally {
    if (pres != null) pres.dispose();
}
```

## **Display Percentage as Labels**
Aspose.Slides for Java allows you to set percentage labels on displayed charts. This Java code demonstrates the operation:

```java
import com.aspose.slides.*;

// Creates an instance of the Presentation class
Presentation pres = new Presentation();
try {
    // Gets the first slide
    ISlide slide = pres.getSlides().get_Item(0);
    
    IChart chart = slide.getShapes().addChart(ChartType.StackedColumn, 20, 20, 400, 400);
    IChartSeries series;
    double[] total_for_Cat = new double[chart.getChartData().getCategories().size()];
    for (int k = 0; k < chart.getChartData().getCategories().size(); k++) {
        IChartCategory cat = chart.getChartData().getCategories().get_Item(k);
    
        for (int i = 0; i < chart.getChartData().getSeries().size(); i++) {
            total_for_Cat[k] = total_for_Cat[k] + (double) (chart.getChartData().getSeries().get_Item(i).getDataPoints().get_Item(k).getValue().getData());
        }
    }
    
    double dataPontPercent = 0f;
    for (int x = 0; x < chart.getChartData().getSeries().size(); x++) {
        series = chart.getChartData().getSeries().get_Item(x);
        series.getLabels().getDefaultDataLabelFormat().setShowLegendKey(false);
    
        for (int j = 0; j < series.getDataPoints().size(); j++) {
            IDataLabel lbl = series.getDataPoints().get_Item(j).getLabel();
            dataPontPercent = (double) ((series.getDataPoints().get_Item(j).getValue().getData())) / (double) (total_for_Cat[j]) * 100;
    
            IPortion port = new Portion();
            port.setText(String.format("%.2f %%", dataPontPercent));
            port.getPortionFormat().setFontHeight(8f);
            lbl.getTextFrameForOverriding().setText("");
            IParagraph para = lbl.getTextFrameForOverriding().getParagraphs().get_Item(0);
            para.getPortions().add(port);
    
            lbl.getDataLabelFormat().setShowSeriesName(false);
            lbl.getDataLabelFormat().setShowPercentage(false);
            lbl.getDataLabelFormat().setShowLegendKey(false);
            lbl.getDataLabelFormat().setShowCategoryName(false);
            lbl.getDataLabelFormat().setShowBubbleSize(false);
        }
    }
    
    // Saves the presentation containing the chart
    pres.save("output.pptx", SaveFormat.Pptx);
} finally {
    if (pres != null) pres.dispose();
}
```

## **Set Percentage Sign with Chart Data Labels**
This Java code shows you to set the percentage sign for a chart data label:

```java
import com.aspose.slides.*;
import java.awt.Color;

// Creates an instance of the Presentation class
Presentation pres = new Presentation();
try {
    // Gets a slide's reference through its index
    ISlide slide = pres.getSlides().get_Item(0);
    
    // Creates the PercentsStackedColumn chart on a slide
    IChart chart = slide.getShapes().addChart(ChartType.PercentsStackedColumn, 20, 20, 500, 400);
    
    // Sets the NumberFormatLinkedToSource to false
    chart.getAxes().getVerticalAxis().setNumberFormatLinkedToSource(false);
    chart.getAxes().getVerticalAxis().setNumberFormat("0.00%");
    
    chart.getChartData().getSeries().clear();
    int defaultWorksheetIndex = 0;
    
    // Gets the chart data worksheet
    IChartDataWorkbook workbook = chart.getChartData().getChartDataWorkbook();
    
    // Adds new series
    IChartSeries series = chart.getChartData().getSeries().add(workbook.getCell(defaultWorksheetIndex, 0, 1, "Reds"), chart.getType());
    series.getDataPoints().addDataPointForBarSeries(workbook.getCell(defaultWorksheetIndex, 1, 1, 0.30));
    series.getDataPoints().addDataPointForBarSeries(workbook.getCell(defaultWorksheetIndex, 2, 1, 0.50));
    series.getDataPoints().addDataPointForBarSeries(workbook.getCell(defaultWorksheetIndex, 3, 1, 0.80));
    series.getDataPoints().addDataPointForBarSeries(workbook.getCell(defaultWorksheetIndex, 4, 1, 0.65));
    
    // Sets the fill color of series
    series.getFormat().getFill().setFillType(FillType.Solid);
    series.getFormat().getFill().getSolidFillColor().setColor(Color.RED);
    
    // Sets the LabelFormat properties
    series.getLabels().getDefaultDataLabelFormat().setShowValue(true);
    series.getLabels().getDefaultDataLabelFormat().setNumberFormatLinkedToSource(false);
    series.getLabels().getDefaultDataLabelFormat().setNumberFormat("0.0%");
    series.getLabels().getDefaultDataLabelFormat().getTextFormat().getPortionFormat().setFontHeight(10);
    series.getLabels().getDefaultDataLabelFormat().getTextFormat().getPortionFormat().getFillFormat().setFillType(FillType.Solid);
    series.getLabels().getDefaultDataLabelFormat().getTextFormat().getPortionFormat().getFillFormat().getSolidFillColor().setColor(Color.WHITE);
    series.getLabels().getDefaultDataLabelFormat().setShowValue(true);
    
    // Adds new series
    IChartSeries series2 = chart.getChartData().getSeries().add(workbook.getCell(defaultWorksheetIndex, 0, 2, "Blues"), chart.getType());
    series2.getDataPoints().addDataPointForBarSeries(workbook.getCell(defaultWorksheetIndex, 1, 2, 0.70));
    series2.getDataPoints().addDataPointForBarSeries(workbook.getCell(defaultWorksheetIndex, 2, 2, 0.50));
    series2.getDataPoints().addDataPointForBarSeries(workbook.getCell(defaultWorksheetIndex, 3, 2, 0.20));
    series2.getDataPoints().addDataPointForBarSeries(workbook.getCell(defaultWorksheetIndex, 4, 2, 0.35));
    
    // Sets Fill type and color
    series2.getFormat().getFill().setFillType(FillType.Solid);
    series2.getFormat().getFill().getSolidFillColor().setColor(Color.BLUE);
    series2.getLabels().getDefaultDataLabelFormat().setShowValue(true);
    series2.getLabels().getDefaultDataLabelFormat().setNumberFormatLinkedToSource(false);
    series2.getLabels().getDefaultDataLabelFormat().setNumberFormat("0.0%");
    series2.getLabels().getDefaultDataLabelFormat().getTextFormat().getPortionFormat().setFontHeight(10);
    series2.getLabels().getDefaultDataLabelFormat().getTextFormat().getPortionFormat().getFillFormat().setFillType(FillType.Solid);
    series2.getLabels().getDefaultDataLabelFormat().getTextFormat().getPortionFormat().getFillFormat().getSolidFillColor().setColor(Color.WHITE);
    
    // Writes the presentation to disk
    pres.save("SetDataLabelsPercentageSign_out.pptx", SaveFormat.Pptx);
} finally {
    if (pres != null) pres.dispose();
}
```

## **Set Label Distance from an Axis**
This Java code shows you how to set the label distance from a category axis when you are dealing with a chart plotted from axes:

```java
import com.aspose.slides.*;

// Creates an instance of the Presentation class
Presentation pres = new Presentation();
try {
    // Gets a slide's reference
    ISlide sld = pres.getSlides().get_Item(0);
    
    // Creates a chart on the slide
    IChart ch = sld.getShapes().addChart(ChartType.ClusteredColumn, 20, 20, 500, 300);
    
    // Sets the label distance from an axis
    ch.getAxes().getHorizontalAxis().setLabelOffset(500);
    
    // WriteS the presentation to disk
    pres.save("output.pptx", SaveFormat.Pptx);
} finally {
    if (pres != null) pres.dispose();
}
```

## **Adjust Label Location**

When you create a chart that does not rely on any axis such as a pie chart, the chart's data labels may end up being too close to its edge. In such a case, you have to adjust the location of the data label so that the leader lines get displayed clearly.

This Java code shows you how to adjust the label location on a pie chart:

```java
import com.aspose.slides.*;

Presentation pres = new Presentation();
try {
    IChart chart = pres.getSlides().get_Item(0).getShapes().addChart(ChartType.Pie, 50, 50, 200, 200);

    IChartSeriesCollection series = chart.getChartData().getSeries();
    IDataLabel label = series.get_Item(0).getLabels().get_Item(0);

    label.getDataLabelFormat().setShowValue(true);
    label.getDataLabelFormat().setPosition(LegendDataLabelPosition.OutsideEnd);
    label.setX(0.71f);
    label.setY(0.04f);

    pres.save("pres.pptx", SaveFormat.Pptx);
} finally {
    if (pres != null) pres.dispose();
}
```

![pie-chart-adjusted-label](pie-chart-adjusted-label.png)

## **FAQ**

### How can I prevent data labels from overlapping on dense charts?

Combine automatic label placement, leader lines, and reduced font size; if necessary, hide some fields (for example, the category) or show labels only for extreme/key points.

### How can I disable labels only for zero, negative, or empty values?

Filter data points before enabling labels and turn off display for values of 0, negative values, or missing values according to a defined rule.

### How can I ensure a consistent label style when exporting to PDF/images?

Explicitly set fonts (family, size) and verify that the font is available on the rendering side to avoid fallback.