我正在使用JasperReports 6.2.2版本。我想隐藏图像，如果该值为null或为空。
下面我在jrxml中使用的代码隐藏了图像，但这对我不起作用。
<image>
<reportElement x="33" y="0" width="88" height="45" uuid="182b40f8-b18e-417c-b9f4-096199533567">
<printWhenExpression><![CDATA[($F{urlImage}!=null ? $F{urlImage} : "")]]></printWhenExpression>
</reportElement>
</image>
$ F {urlImage}是字符串类型
它给出了一个错误
ERROR [btpool0-2] (JRFillSubreport.java:866) - Fill 1: exception
[java] java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Boolean
[java] at net.sf.jasperreports.engine.fill.JRFillElement.evaluatePrintWhenExpression(JRFillElement.java:806)
[java] at net.sf.jasperreports.engine.fill.JRFillImage.evaluate(JRFillImage.java:471)
[java] at net.sf.jasperreports.engine.fill.JRFillElementContainer.evaluate(JRFillElementContainer.java:381)
[java] at net.sf.jasperreports.engine.fill.JRFillFrame.evaluate(JRFillFrame.java:159)
[java] at net.sf.jasperreports.engine.fill.JRFillElementContainer.evaluate(JRFillElementContainer.java:381)
[java] at net.sf.jasperreports.engine.fill.JRFillBand.evaluate(JRFillBand.java:500)
[java] at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillColumnBand(JRVerticalFiller.java:2022)
[java] at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillDetail(JRVerticalFiller.java:748)
[java] at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReportStart(JRVerticalFiller.java:255)
[java] java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Boolean
[java] at net.sf.jasperreports.engine.fill.JRFillElement.evaluatePrintWhenExpression(JRFillElement.java:806)
[java] at net.sf.jasperreports.engine.fill.JRFillImage.evaluate(JRFillImage.java:471)
[java] at net.sf.jasperreports.engine.fill.JRFillElementContainer.evaluate(JRFillElementContainer.java:381)
[java] at net.sf.jasperreports.engine.fill.JRFillFrame.evaluate(JRFillFrame.java:159)
[java] at net.sf.jasperreports.engine.fill.JRFillElementContainer.evaluate(JRFillElementContainer.java:381)
[java] at net.sf.jasperreports.engine.fill.JRFillBand.evaluate(JRFillBand.java:500)
[java] at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillColumnBand(JRVerticalFiller.java:2022)
[java] at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillDetail(JRVerticalFiller.java:748)
[java] at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReportStart(JRVerticalFiller.java:255)
[java] at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReport(JRVerticalFiller.java:115)
[java] at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(JRBaseFiller.java:580)
[java] at net.sf.jasperreports.engine.fill.BaseReportFiller.fill(BaseReportFiller.java:414)
[java] at net.sf.jasperreports.engine.fill.JRFillSubreport.fillSubreport(JRFillSubreport.java:736)
[java] at net.sf.jasperreports.engine.fill.JRSubreportRunnable.run(JRSubreportRunnable.java:59)
[java] at net.sf.jasperreports.engine.fill.AbstractThreadSubreportRunner.run(AbstractThreadSubreportRunner.java:221)
[java] at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
[java] at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
[java] at java.lang.Thread.run(Unknown Source)
[java] at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReport(JRVerticalFiller.java:115)
[java] at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(JRBaseFiller.java:580)
[java] at net.sf.jasperreports.engine.fill.BaseReportFiller.fill(BaseReportFiller.java:414)
[java] at net.sf.jasperreports.engine.fill.JRFillSubreport.fillSubreport(JRFillSubreport.java:736)
[java] at net.sf.jasperreports.engine.fill.JRSubreportRunnable.run(JRSubreportRunnable.java:59)
[java] at net.sf.jasperreports.engine.fill.AbstractThreadSubreportRunner.run(AbstractThreadSubreportRunner.java:221)
[java] at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
[java] at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
[java] at java.lang.Thread.run(Unknown Source)
如果其值为null或为空，如何隐藏图像。在urlImage字段中包含图像的url。例如：“ [http://use.example.com/pop.png][1]”。
最佳答案
printWhenExpression应该返回Boolean，当前您正在返回String$F{urlImage}!=null ? $F{urlImage} : ""是ternary表达式，如果不为null，则返回$F{urlImage}的值，否则返回空字符串
取而代之的是，您只需要返回一个Boolean，因此您将需要这样的表达式：
<printWhenExpression>
<![CDATA[$F{urlImage}!=null && !$F{urlImage}.isEmpty()]]>
</printWhenExpression>
不为空且不为空时打印
注意：使用旧的jasper-reports lib不会自动autobox
您需要自己创建布尔对象
new Boolean($F{urlImage}!=null && !$F{urlImage}.isEmpty())