java - Calculation of BigDecimal -

i'm having problem getting calculation down. can addition, subtract, etc... i'm trying ((a - b)/b) in jasper reports.

here's i've tried far

${budget}.subtract($f{actual})/$f{budget} 

but when compile it. says have expression problem. i'm using jasper studio expression editor

both $f{budget} , $f{actual} text fields , class java.math.bigdecimal

here's stace trace

net.sf.jasperreports.engine.jrexception: net.sf.jasperreports.engine.fill.jrexpressionevalexception: error evaluating expression :  source text : $f{budgeted}.subtract($f{actual}.divide($f{budgeted}))  @ com.jaspersoft.studio.editor.preview.view.control.reportcontroler.fillreport(reportcontroler.java:475)  @ com.jaspersoft.studio.editor.preview.view.control.reportcontroler.access$18(reportcontroler.java:450)  @ com.jaspersoft.studio.editor.preview.view.control.reportcontroler$4.run(reportcontroler.java:337)  @ org.eclipse.core.internal.jobs.worker.run(worker.java:53)      caused by: net.sf.jasperreports.engine.fill.jrexpressionevalexception: error evaluating expression :  source text : $f{budgeted}.subtract($f{actual}.divide($f{budgeted}))  @ net.sf.jasperreports.engine.fill.jrevaluator.evaluateestimated(jrevaluator.java:308)  @ net.sf.jasperreports.engine.fill.jrcalculator.evaluateestimated(jrcalculator.java:582)  @ net.sf.jasperreports.engine.fill.jrcalculator.estimatevariables(jrcalculator.java:181)  @ net.sf.jasperreports.engine.fill.jrfilldataset.next(jrfilldataset.java:1261)  @ net.sf.jasperreports.engine.fill.jrfilldataset.next(jrfilldataset.java:1235)  @ net.sf.jasperreports.engine.fill.jrbasefiller.next(jrbasefiller.java:1588)  @ net.sf.jasperreports.engine.fill.jrverticalfiller.fillreport(jrverticalfiller.java:149)  @ net.sf.jasperreports.engine.fill.jrbasefiller.fill(jrbasefiller.java:939)  @         net.sf.jasperreports.engine.fill.basefillhandle$reportfiller.run(basefillhandle.java:120)  @ java.lang.thread.run(unknown source)     caused by: java.lang.arithmeticexception: division 0  @ java.math.bigdecimal.divide(unknown source)  @ projectsummary_1398114778002_614232.evaluateestimated(projectsummary_1398114778002_614232:405)  @ net.sf.jasperreports.engine.fill.jrevaluator.evaluateestimated(jrevaluator.java:295)  ... 9 more 

${budget}.subtract($f{actual}) return bigdecimal reference, cannot use division symbol / because supported primitives (and class wrappers when unboxed). so, should use bigdecimal#divide instead.

${budget}.subtract($f{actual}).divide($f{budget}) 

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from question edit:

caused by: java.lang.arithmeticexception: division zero

your $f{budget} variable should not have 0 value. use ternary operator solve problem:

${budget}.subtract($f{actual}).divide( ($f{budget}.compareto(bigdecimal.zero) == 0 ? bigdecimal.one : $f{budget}) ) 

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from new comment:

i need if $f{budget} 0 calculation field gets assigned 0 , number other wise.

just modify usage of ternary operator:

($f{budget} == null || $f{budget}.compareto(bigdecimal.zero) == 0)) ? bigdecimal.zero : $f{budget}.subtract($f{actual}).divide($f{budget})