Jasper report with dynamic number of subreports [duplicate] - jasper-reports

Question

I have this set of records:
colors table.
color_group | color_name | color_no
Primary | Red | 1
Primary | Blue | 3
Primary | Yellow | 2
Secondary | Green | 8
Secondary | Violet | 1
Secondary | Orange | 7
Others | Pink | 6
Others | White | 4
Others | Black | 5
I want to generate report like this.
Primary
Red 1
Blue 3
Yellow 2
Secondary
Green 8
Violet 1
Orange 7
Others
Pink 6
White 5
Black 4
how can i display it like this in jasper report?

Answer 1

This is solved by using group on the color_group field and adding a groupHeader band to display its value.
Example
<?xml version="1.0" encoding="UTF-8"?>
<jasperReport xmlns="http://jasperreports.sourceforge.net/jasperreports" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports http://jasperreports.sourceforge.net/xsd/jasperreport.xsd" name="group" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20" uuid="c1d9b4b7-6162-4b17-b871-3cf3b867d1ef">
<field name="color_group" class="java.lang.String"/>
<field name="color_name" class="java.lang.String"/>
<field name="color_no" class="java.lang.Integer"/>
<group name="colorGroup">
<groupExpression><![CDATA[$F{color_group}]]></groupExpression>
<groupHeader>
<band height="20">
<textField>
<reportElement x="0" y="0" width="100" height="20" uuid="e98d6fc1-1ecd-4af4-8250-d8aaa497011e"/>
<textFieldExpression><![CDATA[$F{color_group}]]></textFieldExpression>
</textField>
</band>
</groupHeader>
</group>
<detail>
<band height="20" splitType="Stretch">
<textField>
<reportElement x="20" y="0" width="100" height="20" uuid="7ca1ac35-6249-4ba6-ac87-031f8d410d2e"/>
<textFieldExpression><![CDATA[$F{color_name}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="120" y="0" width="100" height="20" uuid="395b0cdd-4d2c-4d0b-93cd-7cad6daf3a4b"/>
<textFieldExpression><![CDATA[$F{color_no}]]></textFieldExpression>
</textField>
</band>
</detail>
</jasperReport>
Result

Answer 2

As per my knowledge this is the process to create and use group in iReport.
*Write desired query to fetch fields.
*Go to report name -> right click -> add report group ->
specify group name and group by object(in group-criteria) -> next ->
add group-header and footer if needed(in details) -> finish.
*Use this group where ever necessary(by using 'print when group' expression
as created group).