compile-reports (default) on project prs-reporting: Error compiling report design - jasper-reports

Question

How can i fix this error to compile this report. Can anyone explain to me about field not found error. I am very newbie in ireport and this is my first time and this is frustratin. BTW, in my report i want to output the java.util.List data in my report. please help me.
my error trace:
net.sf.jasperreports.engine.design.JRValidationException: Report design not valid :       1. Field not found : itemDescs      2. Field not found : quantity      3. Field not found : units      4. Field not found : requestReason
    at net.sf.jasperreports.engine.design.JRAbstractCompiler.verifyDesign(JRAbstractCompiler.java:258)
    at net.sf.jasperreports.engine.design.JRAbstractCompiler.compileReport(JRAbstractCompiler.java:140)
    at com.jaspersoft.ireport.designer.compiler.IReportCompiler.run(IReportCompiler.java:498)
    at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:572)
    at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:997)
my xml
<?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="PurchaseRequestReport" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20">
<subDataset name="ItemDescription">
<queryString>
<![CDATA[]]>
</queryString>
<field name="itemDescs" class="java.lang.String">
<fieldDescription><![CDATA[_THIS]]></fieldDescription>
</field>
</subDataset>
<subDataset name="Quantity">
<field name="quantity" class="java.lang.String">
<fieldDescription><![CDATA[_THIS]]></fieldDescription>
</field>
</subDataset>
<subDataset name="Unit">
<field name="units" class="java.lang.String">
<fieldDescription><![CDATA[_THIS]]></fieldDescription>
</field>
</subDataset>
<subDataset name="RequestReason">
<field name="requestReason" class="java.lang.String">
<fieldDescription><![CDATA[_THIS]]></fieldDescription>
</field>
</subDataset>
<subDataset name="dataset1"/>
<subDataset name="dataset2"/>
<subDataset name="dataset3"/>
<subDataset name="dataset4"/>
<field name="reqUnit" class="java.lang.String"/>
<field name="reqNum" class="java.lang.String"/>
<field name="reqDate" class="java.lang.String"/>
<field name="localNum" class="java.lang.String"/>
<field name="capex" class="java.lang.String"/>
<field name="capexCode" class="java.lang.String"/>
<field name="justification" class="java.lang.String"/>
<field name="itemDesc" class="java.util.List"/>
<field name="qty" class="java.util.List"/>
<field name="unit" class="java.util.List"/>
<field name="reqReason" class="java.util.List"/>
<field name="remarks" class="java.lang.String"/>
<field name="prepareBy" class="java.lang.String"/>
<field name="noteBy" class="java.lang.String"/>
<field name="approveBy" class="java.lang.String"/>
<background>
<band splitType="Stretch"/>
</background>
<detail>
<band height="802" splitType="Stretch">
<staticText>
<reportElement x="0" y="0" width="555" height="20"/>
<textElement textAlignment="Center"/>
<text><![CDATA[ST. LUKE'S MEDICAL CENTER]]></text>
</staticText>
<staticText>
<reportElement x="0" y="13" width="555" height="20"/>
<textElement textAlignment="Center"/>
<text><![CDATA[PURCHASE REQUISITION]]></text>
</staticText>
<staticText>
<reportElement x="0" y="28" width="555" height="20"/>
<textElement textAlignment="Center"/>
<text><![CDATA[(For Non-Stock Items)]]></text>
</staticText>
<staticText>
<reportElement x="0" y="47" width="343" height="28"/>
<box leftPadding="3">
<pen lineWidth="1.0"/>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<text><![CDATA[Request Number : ]]></text>
</staticText>
<staticText>
<reportElement x="0" y="75" width="343" height="28"/>
<box leftPadding="3">
<pen lineWidth="1.0"/>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<text><![CDATA[Requesting Unit :]]></text>
</staticText>
<staticText>
<reportElement x="343" y="47" width="212" height="28"/>
<box leftPadding="3">
<pen lineWidth="1.0"/>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<text><![CDATA[Date :]]></text>
</staticText>
<staticText>
<reportElement x="343" y="75" width="212" height="28"/>
<box leftPadding="3">
<pen lineWidth="1.0"/>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<text><![CDATA[Local Number :]]></text>
</staticText>
<rectangle>
<reportElement x="0" y="103" width="555" height="78"/>
</rectangle>
<staticText>
<reportElement x="0" y="104" width="344" height="28"/>
<box leftPadding="3"/>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<text><![CDATA[Capital Expenditure :]]></text>
</staticText>
<staticText>
<reportElement x="343" y="104" width="212" height="28"/>
<box leftPadding="3"/>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<text><![CDATA[Capex Code :]]></text>
</staticText>
<staticText>
<reportElement x="0" y="131" width="555" height="50"/>
<box leftPadding="3"/>
<textElement>
<font size="12"/>
</textElement>
<text><![CDATA[Justification :]]></text>
</staticText>
<rectangle>
<reportElement x="0" y="181" width="555" height="304"/>
</rectangle>
<staticText>
<reportElement x="0" y="182" width="235" height="20"/>
<box leftPadding="3"/>
<textElement>
<font size="12"/>
</textElement>
<text><![CDATA[ITEM DESCRIPTION]]></text>
</staticText>
<staticText>
<reportElement x="234" y="182" width="52" height="20"/>
<textElement textAlignment="Center" verticalAlignment="Top">
<font size="12"/>
</textElement>
<text><![CDATA[QTY]]></text>
</staticText>
<staticText>
<reportElement x="285" y="182" width="70" height="20"/>
<textElement textAlignment="Center" verticalAlignment="Top">
<font size="12"/>
</textElement>
<text><![CDATA[UNIT]]></text>
</staticText>
<staticText>
<reportElement x="354" y="182" width="201" height="20"/>
<box leftPadding="3"/>
<textElement>
<font size="12"/>
</textElement>
<text><![CDATA[REQUEST REASON]]></text>
</staticText>
<componentElement>
<reportElement stretchType="RelativeToBandHeight" x="0" y="201" width="235" height="49" isRemoveLineWhenBlank="true" isPrintInFirstWholeBand="true" isPrintWhenDetailOverflows="true"/>
<jr:list xmlns:jr="http://jasperreports.sourceforge.net/jasperreports/components" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports/components http://jasperreports.sourceforge.net/xsd/components.xsd" printOrder="Vertical">
<datasetRun subDataset="dataset1">
<dataSourceExpression><![CDATA[new net.sf.jasperreports.engine.JREmptyDataSource(1)]]></dataSourceExpression>
</datasetRun>
<jr:listContents height="49" width="235">
<textField isStretchWithOverflow="true">
<reportElement x="0" y="0" width="235" height="49"/>
<box leftPadding="3"/>
<textElement>
<font size="12"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$F{itemDescs}]]></textFieldExpression>
</textField>
</jr:listContents>
</jr:list>
</componentElement>
<componentElement>
<reportElement stretchType="RelativeToBandHeight" x="234" y="201" width="52" height="49" isRemoveLineWhenBlank="true" isPrintInFirstWholeBand="true" isPrintWhenDetailOverflows="true"/>
<jr:list xmlns:jr="http://jasperreports.sourceforge.net/jasperreports/components" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports/components http://jasperreports.sourceforge.net/xsd/components.xsd" printOrder="Vertical">
<datasetRun subDataset="dataset2">
<dataSourceExpression><![CDATA[new net.sf.jasperreports.engine.JREmptyDataSource(1)]]></dataSourceExpression>
</datasetRun>
<jr:listContents height="49" width="52">
<textField isStretchWithOverflow="true">
<reportElement x="0" y="0" width="52" height="49"/>
<textElement textAlignment="Center">
<font size="12"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$F{quantity}]]></textFieldExpression>
</textField>
</jr:listContents>
</jr:list>
</componentElement>
<componentElement>
<reportElement stretchType="RelativeToBandHeight" x="285" y="201" width="70" height="49" isRemoveLineWhenBlank="true" isPrintInFirstWholeBand="true" isPrintWhenDetailOverflows="true"/>
<jr:list xmlns:jr="http://jasperreports.sourceforge.net/jasperreports/components" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports/components http://jasperreports.sourceforge.net/xsd/components.xsd" printOrder="Vertical">
<datasetRun subDataset="dataset3">
<dataSourceExpression><![CDATA[new net.sf.jasperreports.engine.JREmptyDataSource(1)]]></dataSourceExpression>
</datasetRun>
<jr:listContents height="49" width="70">
<textField isStretchWithOverflow="true">
<reportElement x="0" y="0" width="70" height="49"/>
<textElement textAlignment="Center">
<font size="12"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$F{units}]]></textFieldExpression>
</textField>
</jr:listContents>
</jr:list>
</componentElement>
<componentElement>
<reportElement stretchType="RelativeToBandHeight" x="354" y="201" width="201" height="49" isRemoveLineWhenBlank="true" isPrintInFirstWholeBand="true" isPrintWhenDetailOverflows="true"/>
<jr:list xmlns:jr="http://jasperreports.sourceforge.net/jasperreports/components" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports/components http://jasperreports.sourceforge.net/xsd/components.xsd" printOrder="Vertical">
<datasetRun subDataset="dataset4">
<dataSourceExpression><![CDATA[new net.sf.jasperreports.engine.JREmptyDataSource(1)]]></dataSourceExpression>
</datasetRun>
<jr:listContents height="49" width="201">
<textField isStretchWithOverflow="true">
<reportElement x="0" y="0" width="201" height="49"/>
<box leftPadding="3"/>
<textElement>
<font size="12"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$F{requestReason}]]></textFieldExpression>
</textField>
</jr:listContents>
</jr:list>
</componentElement>
<staticText>
<reportElement x="0" y="425" width="555" height="60"/>
<box leftPadding="3"/>
<textElement>
<font size="12"/>
</textElement>
<text><![CDATA[Remarks :]]></text>
</staticText>
<staticText>
<reportElement x="0" y="485" width="286" height="35"/>
<box leftPadding="3">
<pen lineWidth="1.0"/>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<text><![CDATA[Prepared By :]]></text>
</staticText>
<staticText>
<reportElement x="0" y="520" width="286" height="35"/>
<box leftPadding="3">
<pen lineWidth="1.0"/>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<text><![CDATA[Noted By :]]></text>
</staticText>
<staticText>
<reportElement x="286" y="485" width="269" height="35"/>
<box leftPadding="3">
<pen lineWidth="1.0"/>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<text><![CDATA[Checked By :]]></text>
</staticText>
<staticText>
<reportElement x="286" y="520" width="269" height="35"/>
<box leftPadding="3">
<pen lineWidth="1.0"/>
<topPen lineWidth="1.0"/>
<leftPen lineWidth="1.0"/>
<bottomPen lineWidth="1.0"/>
<rightPen lineWidth="1.0"/>
</box>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<text><![CDATA[Approved By :]]></text>
</staticText>
<textField>
<reportElement x="99" y="75" width="244" height="29"/>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$F{reqUnit}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="105" y="48" width="238" height="27"/>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$F{reqNum}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="379" y="47" width="176" height="28"/>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$F{reqDate}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="431" y="75" width="124" height="28"/>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$F{localNum}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="118" y="103" width="225" height="28"/>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$F{capex}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="422" y="104" width="133" height="27"/>
<textElement verticalAlignment="Middle">
<font size="12"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$F{capexCode}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="77" y="132" width="478" height="49"/>
<textElement>
<font size="12"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$F{justification}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="66" y="425" width="488" height="60"/>
<textElement>
<font size="12"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$F{remarks}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="77" y="485" width="209" height="35"/>
<textElement/>
<textFieldExpression class="java.lang.String"><![CDATA[$F{prepareBy}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="77" y="520" width="209" height="35"/>
<textElement/>
<textFieldExpression class="java.lang.String"><![CDATA[$F{noteBy}]]></textFieldExpression>
</textField>
<textField>
<reportElement x="365" y="520" width="189" height="35"/>
<textElement/>
<textFieldExpression class="java.lang.String"><![CDATA[$F{approveBy}]]></textFieldExpression>
</textField>
</band>
</detail>
</jasperReport>

Answer 1

your list contains object(class) , this object have fields, you must put the same name of these fields and set their data type on your reportName.jrxml as is in your class.
if there is a field in your class that is itself another object or classe you must use steps
your classe contains a field product and product has a field qte
in your report fields put product.qte

Answer 2

You are getting the fields from their respective datasets. As you dont have any fields defined in dataset it is throwing this exception
JRValidationException: Report design not valid :
1. Field not found : itemDescs
2. Field not found : quantity
3. Field not found : units
4. Field not found : requestReason
from error it is clear that this fields are not available
to fix the validation exception add above fields in their respective datasets (dataset you assigned for each list component).
here is the code:
<subDataset name="dataset1">
<field name="itemDescs" class="java.lang.String"/>
</subDataset>
<subDataset name="dataset2">
<field name="quantity" class="java.lang.String"/>
</subDataset>
<subDataset name="dataset3">
<field name="units" class="java.lang.String"/>
</subDataset>
<subDataset name="dataset4">
<field name="requestReason" class="java.lang.String"/>
</subDataset>
And you'll not get this JRValidationException.