正确的表达式是：

  new java.text.DecimalFormat（$＃，## 0.00）。format（Double.valueOf（$ P {strParam}））
 

java.lang.Integer 和 java.lang.String 的工作示例 ： UTF-8\" &GT？;
< jasperReport xmlns =http://jasperreports.sourceforge.net/jasperreportsxmlns：xsi =http://www.w3.org/2001/XMLSchema-instancexsi：schemaLocation =http： //www.jasperreports.sourceforge.net/jasperreports.xsdname =format_as_currentpageWidth =595pageHeight =842whenNoDataType =AllSectionsNoDetailcolumnWidth =555 leftMargin =20rightMargin =20topMargin =20bottomMargin =20>
< parameter name =intParamclass =java.lang.Integer>
< defaultValueExpression><！[CDATA [12345678]]>< / defaultValueExpression>
< / parameter>
< parameter name =strParamclass =java.lang.String>
< defaultValueExpression><！[CDATA [12345678.95]]>< / defaultValueExpression>
< / parameter>
< title>
< band height =79splitType =Stretch>
< textField>
< reportElement x =137y =18width =291height =20/>
< textElement />
< textFieldExpression><！[CDATA [new java.text.DecimalFormat（$＃，## 0.00）.format（$ P {intParam}）]]>< / textFieldExpression>
< / textField>
< textField>
< reportElement x =137y =48width =291height =20/>
< textElement />
<！[CDATA [new java.text.DecimalFormat（$＃，## 0.00）。format（Double.valueOf（$ P {strParam}！= null&& $ P {strParam} .length（）> 0？Double.valueOf（$ P {strParam}）：0））]]>< / textFieldExpression>
< / textField>
< / band>
< / title>
< / jasperReport>

结果将会是（在 iReport 中预览）：

$ b

注意：
您还应该添加检查null。

您也可以使用 textField 的 pattern 属性来设置数据的格式。

示例：
$ b

 <？xml version =1.0encoding =UTF-8？ &GT; 
< jasperReport xmlns =http://jasperreports.sourceforge.net/jasperreportsxmlns：xsi =http://www.w3.org/2001/XMLSchema-instancexsi：schemaLocation =http： //www.jasperreports.sourceforge.net/jasperreports.xsdname =format_as_currentpageWidth =595pageHeight =842whenNoDataType =AllSectionsNoDetailcolumnWidth =555 leftMargin =20rightMargin =20topMargin =20bottomMargin =20> 
< parameter name =intParamclass =java.lang.Integer> 
< defaultValueExpression><！[CDATA [12345678]]>< / defaultValueExpression> 
< / parameter> 
< parameter name =strParamclass =java.lang.String> 
< defaultValueExpression><！[CDATA [12345678.95]]>< / defaultValueExpression> 
< / parameter> 
< title> 
< band height =148splitType =Stretch> 
< textField pattern =$＃，## 0.00> 
< reportElement x =218y =99width =100height =20/> 
< textElement /> 
< textFieldExpression><！[CDATA [$ P {intParam}]]>< / textFieldExpression> 
< / textField> 
< textField pattern =$＃，## 0.00> 
< reportElement x =218y =119width =100height =20/> 
< textElement /> 
< textFieldExpression><！[CDATA [$ P {strParam}！= null&& $ P {strParam} .length（）> 0？ Double.valueOf（$ P {strParam}）：0]]>< / textFieldExpression> 
< / textField> 
< / band> 
< / title> 
< / jasperReport> 
 

结果是一样的。

I have a string with some numeric value.

I want to format it in a way where hundreds are comma separated and the number is having $ dollar sign before it.

e.g. 12345 should be formatted to $ 12,345.00

I tried the below code without dollar sign:

new java.text.DecimalFormat(#,##0.00).format.(myString)

and the below one with dollar sign:

new java.text.DecimalFormat($ #,##0.00).format.(myString)

However, both are giving error.

What is the right way to achieve this format ?

This is a part of jasper report jrxml where I want to avoid "null" on the report and thus inserting the below code:

<textField isBlankWhenNull="false" isStretchWithOverflow="true">            
  <reportElement stretchType="RelativeToTallestObject" x="1350" y="0" width="150" height="30"/>             
      <textElement/>             
   <textFieldExpression class="java.math.BigDecimal"><![CDATA[$F{myString}!=null?new java.text.DecimalFormat(#,##0.00).format.($F{myString}):"Unavailable"]]></textFieldExpression>        
</textField>

Where myString results from a query and is declared in jrxml as:

 <field name="myString" class="java.lang.String"/>

Earlier myString was declared as BigDecimal, but then comparison operator ?= was not working.

If the currency value is not available, I want to print "unavailable" on the report instead of default "null". Else, I want the number to be properly formatted as described above.

How to resolve this issue?

Thanks for reading.

The correct expression is:

new java.text.DecimalFormat("$ #,##0.00").format(Double.valueOf($P{strParam}))

The working sample for java.lang.Integer and java.lang.String:

<?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="format_as_current" pageWidth="595" pageHeight="842" whenNoDataType="AllSectionsNoDetail" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20">
    <parameter name="intParam" class="java.lang.Integer">
        <defaultValueExpression><![CDATA[12345678]]></defaultValueExpression>
    </parameter>
    <parameter name="strParam" class="java.lang.String">
        <defaultValueExpression><![CDATA["12345678.95"]]></defaultValueExpression>
    </parameter>
    <title>
        <band height="79" splitType="Stretch">
            <textField>
                <reportElement x="137" y="18" width="291" height="20"/>
                <textElement/>
                <textFieldExpression><![CDATA[new java.text.DecimalFormat("$ #,##0.00").format($P{intParam})]]></textFieldExpression>
            </textField>
            <textField>
                <reportElement x="137" y="48" width="291" height="20"/>
                <textElement/>
                <textFieldExpression><![CDATA[new java.text.DecimalFormat("$ #,##0.00").format(Double.valueOf($P{strParam} != null && $P{strParam}.length() > 0 ? Double.valueOf($P{strParam}) : 0))]]></textFieldExpression>
            </textField>
        </band>
    </title>
</jasperReport>

The result will be (preview in iReport):

Note: You should also add check for null.

You can also use pattern property of textField for formatting data.

The sample:

<?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="format_as_current" pageWidth="595" pageHeight="842" whenNoDataType="AllSectionsNoDetail" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20">
    <parameter name="intParam" class="java.lang.Integer">
        <defaultValueExpression><![CDATA[12345678]]></defaultValueExpression>
    </parameter>
    <parameter name="strParam" class="java.lang.String">
        <defaultValueExpression><![CDATA["12345678.95"]]></defaultValueExpression>
    </parameter>
    <title>
        <band height="148" splitType="Stretch">
            <textField pattern="$ #,##0.00">
                <reportElement x="218" y="99" width="100" height="20"/>
                <textElement/>
                <textFieldExpression><![CDATA[$P{intParam}]]></textFieldExpression>
            </textField>
            <textField pattern="$ #,##0.00">
                <reportElement x="218" y="119" width="100" height="20"/>
                <textElement/>
                <textFieldExpression><![CDATA[$P{strParam} != null && $P{strParam}.length() > 0 ? Double.valueOf($P{strParam}) : 0]]></textFieldExpression>
            </textField>
        </band>
    </title>
</jasperReport>

The result will be the same.