JasperReports handle null values

last modified February 12, 2024

In this article we show how to handle null values in JasperReports.

JasperReports is an open-source reporting library. It can create reports in various formats including PDF, HTML, XLS, or CSV. JasperReports creates page-oriented, ready-to-print documents.

Data sources often contain null values. These do not look good in our reports; therefore, we show how to replace them with empty strings or more descriptive messages such as 'N/A'.

<textField isBlankWhenNull="true">

In order to deal with null values, we can set the isBlankWhenNull attribute of the textField to true.

$F{salary} != null ? $F{salary} : 'N/A'

Another option is to use a ternary operator in the textFieldExpression.

class CleanData {

    static String removeNull(def oldval, def newval = '') {
        if (oldval == null) {
            newval
        } else {
            oldval
        }
    }
}

Another option is to define an external method.

Example

In the next example, we use the isBlankWhenNull attribute and the ternary operator.

report.gvy

package com.zetcode

@Grab(group='net.sf.jasperreports', module='jasperreports', version='6.21.0')
@Grab(group='com.github.librepdf', module='openpdf', version='1.3.39')
@Grab(group='com.h2database', module='h2', version='1.4.200')
@GrabConfig(systemClassLoader=true)

import net.sf.jasperreports.engine.JasperCompileManager
import net.sf.jasperreports.engine.JasperFillManager
import net.sf.jasperreports.engine.JasperExportManager
import groovy.sql.Sql

def xmlFile = 'report.xml'
def jrReport = JasperCompileManager.compileReport(xmlFile)

def createTable = '''
CREATE TABLE users(id INT PRIMARY KEY AUTO_INCREMENT, name VARCHAR(255), occupation VARCHAR(255), salary INT);
INSERT INTO users(name, occupation, salary) VALUES('John Doe', 'gardener', NULL);
INSERT INTO users(name, occupation, salary) VALUES('Roger Roe', 'driver', 940);
INSERT INTO users(name, occupation, salary) VALUES('Roman Novy', 'programmer', 1980);
INSERT INTO users(name, occupation, salary) VALUES('Lucia Biela', NULL, NULL);
INSERT INTO users(name, occupation, salary) VALUES('Tomas Gerber', 'soldier', 1250);
INSERT INTO users(name, occupation, salary) VALUES('Maria Smith', 'teacher', NULL);
INSERT INTO users(name, occupation, salary) VALUES('Oleg Vasil', NULL, 2550);
INSERT INTO users(name, occupation, salary) VALUES('Martin Krajci', 'optician', 2050);
'''

def url = "jdbc:h2:mem:"
Sql.withInstance(url) { sql ->

    sql.execute(createTable)

    def params = [:]
    def jPrint = JasperFillManager.fillReport(jrReport, params, sql.connection)

    JasperExportManager.exportReportToPdfFile(jPrint, "report.pdf")
}

We define a users table inside an in-memory H2 database.

def createTable = '''
CREATE TABLE users(id INT PRIMARY KEY AUTO_INCREMENT, name VARCHAR(255), occupation VARCHAR(255), salary INT);
INSERT INTO users(name, occupation, salary) VALUES('John Doe', 'gardener', NULL);
INSERT INTO users(name, occupation, salary) VALUES('Roger Roe', 'driver', 940);
INSERT INTO users(name, occupation, salary) VALUES('Roman Novy', 'programmer', 1980);
INSERT INTO users(name, occupation, salary) VALUES('Lucia Biela', NULL, NULL);
INSERT INTO users(name, occupation, salary) VALUES('Tomas Gerber', 'soldier', 1250);
INSERT INTO users(name, occupation, salary) VALUES('Maria Smith', 'teacher', NULL);
INSERT INTO users(name, occupation, salary) VALUES('Oleg Vasil', NULL, 2550);
INSERT INTO users(name, occupation, salary) VALUES('Martin Krajci', 'optician', 2050);
'''

The table contains nulls in the occupation and salary columns.

report.xml

<?xml version = "1.0" encoding = "UTF-8"?>
<!DOCTYPE jasperReport PUBLIC "//JasperReports//DTD Report Design//EN"
        "http://jasperreports.sourceforge.net/dtds/jasperreport.dtd">

<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"
              language="groovy"
              name="report" topMargin="20" bottomMargin="20">

    <queryString language="SQL">
        <![CDATA[ SELECT id, name, occupation, salary from users ]]>
    </queryString>

    <field name="id" class="java.lang.Integer"/>
    <field name="name"/>
    <field name="occupation"/>
    <field name="salary" class="java.lang.Integer" />

    <title>
        <band height="60">
            <staticText>
                <reportElement x="0" y="0" width="595" height="35"/>
                <textElement textAlignment="Center"/>
                <text><![CDATA[Users]]></text>
            </staticText>
        </band>
    </title>

    <detail>
        <band height="30">

            <textField>
                <reportElement x="0" y="0" width="25" height="25"/>
                <textFieldExpression class="java.lang.Integer">
                    <![CDATA[$F{id}]]>
                </textFieldExpression>
            </textField>

            <textField>
                <reportElement x="30" y="0" width="100" height="25"/>
                <textFieldExpression>
                    <![CDATA[$F{name}]]>
                </textFieldExpression>
            </textField>

            <textField isBlankWhenNull="true">
                <reportElement x="140" y="0" width="70" height="25"/>
                <textFieldExpression>
                    <![CDATA[ $F{occupation} ]]>
                </textFieldExpression>
            </textField>

            <textField>
                <reportElement x="220" y="0" width="70" height="25"/>
                <textElement textAlignment="Right"/>
                <textFieldExpression class="java.lang.Integer">
                    <![CDATA[ $F{salary} != null ? $F{salary} : 'N/A'  ]]>
                </textFieldExpression>
            </textField>

        </band>
    </detail>

</jasperReport>

This is the report template.

<textField isBlankWhenNull="true">
    <reportElement x="140" y="0" width="70" height="25"/>
    <textFieldExpression>
        <![CDATA[ $F{occupation} ]]>
    </textFieldExpression>
</textField>

We set the isBlankWhenNull to true for the occupation field. Cells with null values will be empty.

<textField>
    <reportElement x="220" y="0" width="70" height="25"/>
    <textElement textAlignment="Right"/>
    <textFieldExpression class="java.lang.Integer">
        <![CDATA[ $F{salary} != null ? $F{salary} : 'N/A'  ]]>
    </textFieldExpression>
</textField>

For the salary field, we use a ternary operator. Nulls will be replaced with N/A strings.

In the next example we define an external method that handles nulls.

report.gvy

package com.zetcode

@Grab(group='net.sf.jasperreports', module='jasperreports', version='6.21.0')
@Grab(group='com.github.librepdf', module='openpdf', version='1.3.39')
@Grab(group='net.sf.jasperreports', module='jasperreports-fonts', version='6.21.0')
@Grab(group='com.h2database', module='h2', version='1.4.200')
@GrabConfig(systemClassLoader=true)

import net.sf.jasperreports.engine.JasperCompileManager
import net.sf.jasperreports.engine.JasperFillManager
import net.sf.jasperreports.engine.JasperExportManager
import groovy.sql.Sql

def xmlFile = 'report.xml'
def jrReport = JasperCompileManager.compileReport(xmlFile)

def createTable = '''
CREATE TABLE users(id INT PRIMARY KEY AUTO_INCREMENT, name VARCHAR(255), occupation VARCHAR(255), salary INT);
INSERT INTO users(name, occupation, salary) VALUES('John Doe', 'gardener', NULL);
INSERT INTO users(name, occupation, salary) VALUES('Roger Roe', 'driver', 940);
INSERT INTO users(name, occupation, salary) VALUES('Roman Novy', 'programmer', 1980);
INSERT INTO users(name, occupation, salary) VALUES('Lucia Biela', NULL, NULL);
INSERT INTO users(name, occupation, salary) VALUES('Tomas Gerber', 'soldier', 1250);
INSERT INTO users(name, occupation, salary) VALUES('Maria Smith', 'teacher', NULL);
INSERT INTO users(name, occupation, salary) VALUES('Oleg Vasil', NULL, 2550);
INSERT INTO users(name, occupation, salary) VALUES('Martin Krajci', 'optician', 2050);
'''

def url = "jdbc:h2:mem:"
Sql.withInstance(url) { sql ->

    sql.execute(createTable)

    def params = [:]
    def jPrint = JasperFillManager.fillReport(jrReport, params, sql.connection)

    JasperExportManager.exportReportToPdfFile(jPrint, "report.pdf")
}

class CleanData {

    static String removeNull(def oldval, def newval = '') {
        if (oldval == null) {
            newval
        } else {
            oldval
        }
    }
}

In the Groovy code, we define the CleanData and its removeNull method. It allows us to select a specific message to be used instead of the null.

report.xml

<?xml version = "1.0" encoding = "UTF-8"?>
<!DOCTYPE jasperReport PUBLIC "//JasperReports//DTD Report Design//EN"
        "http://jasperreports.sourceforge.net/dtds/jasperreport.dtd">

<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"
              language="groovy"
              name="report" topMargin="20" bottomMargin="20">

    <import value="com.zetcode.CleanData"/>

    <queryString language="SQL">
        <![CDATA[ SELECT id, name, occupation, salary from users ]]>
    </queryString>

    <field name="id" class="java.lang.Integer"/>
    <field name="name"/>
    <field name="occupation"/>
    <field name="salary" class="java.lang.Integer" />

    <variable name="sumsal" class="java.lang.Integer" calculation="Sum">
        <variableExpression><![CDATA[$F{salary}]]></variableExpression>
    </variable>

    <title>
        <band height="60">
            <staticText>
                <reportElement x="0" y="0" width="595" height="35"/>
                <textElement textAlignment="Center"/>
                <text><![CDATA[Users]]></text>
            </staticText>
        </band>
    </title>

    <detail>
        <band height="30">

            <textField>
                <reportElement x="0" y="0" width="25" height="25"/>
                <textFieldExpression class="java.lang.Integer">
                    <![CDATA[$F{id}]]>
                </textFieldExpression>
            </textField>

            <textField>
                <reportElement x="30" y="0" width="100" height="25"/>
                <textFieldExpression>
                    <![CDATA[$F{name}]]>
                </textFieldExpression>
            </textField>

            <textField>
                <reportElement x="140" y="0" width="70" height="25"/>
                <textFieldExpression>
                    <![CDATA[ CleanData.removeNull($F{occupation}, 'N/A') ]]>
                </textFieldExpression>
            </textField>

            <textField>
                <reportElement x="220" y="0" width="70" height="25"/>
                <textElement textAlignment="Right"/>
                <textFieldExpression>
                    <![CDATA[ CleanData.removeNull($F{salary}, 'N/A') ]]>
                </textFieldExpression>
            </textField>

        </band>
    </detail>

    <summary>
        <band height="25">
            <textField>
                <reportElement x="220" y="0" width="70" height="25"/>
                <textElement textAlignment="Right">
                    <font isBold = "true"/>
                </textElement>
                <textFieldExpression><![CDATA[$V{sumsal}]]></textFieldExpression>
            </textField>
        </band>
    </summary>

</jasperReport>

In this report, we use the external CleanData.removeNull method.

<import value="com.zetcode.CleanData"/>

We import the class to the report.

<textField>
    <reportElement x="140" y="0" width="70" height="25"/>
    <textFieldExpression>
        <![CDATA[ CleanData.removeNull($F{occupation}, 'N/A') ]]>
    </textFieldExpression>
</textField>

We pass the CleanData.removeNull the $F{occupation} value and the optional string to replace the potential null value.

In this article we demonstrated how to replace null values with empty strings or more descriptive messages.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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