SubReport not shown - jasper-reports

Question

I'd like to create a simple Jasper Report, with subreport, but I cannot make it work.
For example, I have two, simple report.
test1.jrxml
<?xml version="1.0" encoding="UTF-8"?>
<!-- Created with Jaspersoft Studio version 6.2.0.final using JasperReports Library version 6.2.0 -->
<!-- 2016-01-18T23:29:14 -->
<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="test1" pageWidth="842" pageHeight="595" orientation="Landscape" columnWidth="802" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20" uuid="553ce57f-5ea7-48e5-8eaa-dcfecf31880a">
<queryString>
<![CDATA[select dummy from dual]]>
</queryString>
<field name="dummy" class="java.lang.String"/>
<background>
<band splitType="Stretch"/>
</background>
<title>
<band height="79" splitType="Stretch"/>
</title>
<pageHeader>
<band height="35" splitType="Stretch"/>
</pageHeader>
<columnHeader>
<band height="61" splitType="Stretch">
<staticText>
<reportElement x="89" y="0" width="100" height="30" uuid="04f9b63d-265b-45f0-a249-41464df6b4c0"/>
<text><![CDATA[x]]></text>
</staticText>
<staticText>
<reportElement x="227" y="0" width="100" height="30" uuid="0c7db454-653c-4dcf-af94-a0f1c9962b91"/>
<text><![CDATA[x]]></text>
</staticText>
<staticText>
<reportElement x="352" y="0" width="100" height="30" uuid="7ad861d5-74ba-49e9-95c7-4cd01d184dbe"/>
<text><![CDATA[x]]></text>
</staticText>
</band>
</columnHeader>
<detail>
<band height="257" splitType="Stretch">
<textField>
<reportElement x="89" y="66" width="100" height="30" uuid="4099071d-8bfc-4e61-a697-af078ccb626a"/>
<textFieldExpression><![CDATA[$F{dummy}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="227" y="68" width="100" height="30" uuid="a955ca4e-aecd-48c3-8b7c-face6295b879"/>
<textFieldExpression><![CDATA[$F{dummy}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="352" y="65" width="100" height="30" uuid="5a998443-ae4f-457d-a565-67b4f3405951"/>
<textFieldExpression><![CDATA[$F{dummy}]]></textFieldExpression>
</textField>
<subreport>
<reportElement x="555" y="57" width="200" height="200" uuid="d6eada20-a566-4ba5-ab51-9d6ea0b4dfd9"/>
<parametersMapExpression><![CDATA[$P{REPORT_PARAMETERS_MAP}]]></parametersMapExpression>
<subreportParameter name="a">
<subreportParameterExpression><![CDATA[12]]></subreportParameterExpression>
</subreportParameter>
<subreportExpression><![CDATA["test4.jasper"]]></subreportExpression>
</subreport>
</band>
</detail>
<columnFooter>
<band height="45" splitType="Stretch"/>
</columnFooter>
<pageFooter>
<band height="54" splitType="Stretch"/>
</pageFooter>
<summary>
<band height="42" splitType="Stretch"/>
</summary>
</jasperReport>
test4.jrxml
<?xml version="1.0" encoding="UTF-8"?>
<!-- Created with Jaspersoft Studio version 6.2.0.final using JasperReports Library version 6.2.0 -->
<!-- 2016-01-18T23:27:56 -->
<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="test4" pageWidth="842" pageHeight="595" orientation="Landscape" columnWidth="802" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20" uuid="c55e71d8-6eb9-4f20-9263-c50c295fa0d1">
<parameter name="a" class="java.lang.String"/>
<queryString>
<![CDATA[select dummy from dual where 1=1]]>
</queryString>
<field name="dummy" class="java.lang.String"/>
<background>
<band splitType="Stretch"/>
</background>
<title>
<band height="79" splitType="Stretch"/>
</title>
<pageHeader>
<band height="35" splitType="Stretch"/>
</pageHeader>
<columnHeader>
<band height="61" splitType="Stretch">
<staticText>
<reportElement x="364" y="0" width="100" height="30" uuid="1d48df0f-3f4c-489f-b479-e981b2727590"/>
<text><![CDATA[b]]></text>
</staticText>
<staticText>
<reportElement x="478" y="0" width="100" height="30" uuid="397b1c60-fe4d-4f41-a7a4-7c585a57ac15"/>
<text><![CDATA[a]]></text>
</staticText>
</band>
</columnHeader>
<detail>
<band height="125" splitType="Stretch">
<staticText>
<reportElement x="239" y="58" width="100" height="30" uuid="5b5c86c0-1b1b-44d3-87cb-2ad2782a3408"/>
<text><![CDATA[test4]]></text>
</staticText>
<textField>
<reportElement x="364" y="66" width="100" height="30" uuid="d3217648-88a1-4d88-b2b0-7f7cc4e598c6"/>
<textFieldExpression><![CDATA[$F{dummy}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="478" y="47" width="100" height="30" uuid="f2c6bfb9-ee73-4928-8ce4-0a83060d0801"/>
<textFieldExpression><![CDATA[$F{dummy}]]></textFieldExpression>
</textField>
</band>
</detail>
<columnFooter>
<band height="45" splitType="Stretch"/>
</columnFooter>
<pageFooter>
<band height="54" splitType="Stretch"/>
</pageFooter>
<summary>
<band height="42" splitType="Stretch"/>
</summary>
</jasperReport>
The selects provide one result (the DB is Oracle), but the subreport isn't visible in the repport made from test1.jrxml. But a whole new, empty page is at the end of the report.
Can you show me what's wrong with this example? I'd tried a lot's of stuff (default value in the subreport, When No Data = All Sections, No Detail setting in the subReport's header, and a lot of stuff, I can't remember), but nothing helped.

Answer 1

In your example I can see two problems:
You need to pass absolute path to subreport (this is normally done by parameter, so that it can be controlled on runtime)
<parameter name="SUBREPORT_DIR" class="java.lang.String" isForPrompting="false">
<defaultValueExpression><![CDATA["C:\\jdd\\projects\\StackTrace\\jasper\\"]]></defaultValueExpression>
</parameter>
<subreportExpression><![CDATA[$P{SUBREPORT_DIR} + "test4.jasper"]]></subreportExpression>
You need to pass the report connection to the subreport
<subreport>
<reportElement x="555" y="57" width="200" height="200" uuid="d6eada20-a566-4ba5-ab51-9d6ea0b4dfd9"/>
<parametersMapExpression><![CDATA[$P{REPORT_PARAMETERS_MAP}]]></parametersMapExpression>
<subreportParameter name="a">
<subreportParameterExpression><![CDATA[12]]></subreportParameterExpression>
</subreportParameter>
<connectionExpression><![CDATA[$P{REPORT_CONNECTION}]]></connectionExpression>
<subreportExpression><![CDATA[$P{SUBREPORT_DIR} + "test4.jasper"]]></subreportExpression>
</subreport>