问题
While running below code, I am getting error. I have no idea what is causing this error.
ScriptEngine engine = engineManager.getEngineByName("nashorn");
String str = "var shape_objects = [ Java.Type(\"new Triangle()\"), Java.Type(\"new Circle()\"), Java.Type(\"new Rectangle()\"), Java.Type(\"new Shape()\")];"+
"var colors = [\"Red\", \"Green\", \"Blue\", \"Abstract\"];"+
"var j = 0;"+
"for(var i in shape_objects) {"+
" shape_objects[i].setColor(colors[j]);"+
" j = j+1;"+
"}"+
"for(var k in shape_objects) {"+
" print(shape_objects[k].getColor());"+
"}";
engine.eval(str);
// Class definition for other Shape classes is similar
public class Circle {
private String color;
public String setColor(String color) {
this.color = new String(color);
System.out.println("Color of Circle is set to : " + this.color);
return this.color;
}
public String getColor() {
return color;
}
}
Error description:
Exception in thread "main" javax.script.ScriptException: TypeError:
Cannot call undefined in <eval> at line number 1
at jdk.nashorn.api.scripting.NashornScriptEngine.throwAsScriptException(NashornScriptEngine.java:455)
at jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:439)
at jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:401)
at jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:397)
at jdk.nashorn.api.scripting.NashornScriptEngine.eval(NashornScriptEngine.java:152)
at javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:264)
at nashorntest.Test.main(Test.java:40)
Caused by: <eval>:1 TypeError: Cannot call undefined
at jdk.nashorn.internal.runtime.ECMAErrors.error(ECMAErrors.java:57)
at jdk.nashorn.internal.runtime.ECMAErrors.typeError(ECMAErrors.java:213)
at jdk.nashorn.internal.runtime.ECMAErrors.typeError(ECMAErrors.java:185)
at jdk.nashorn.internal.runtime.ECMAErrors.typeError(ECMAErrors.java:172)
at jdk.nashorn.internal.runtime.Undefined.lookupTypeError(Undefined.java:128)
at jdk.nashorn.internal.runtime.Undefined.lookup(Undefined.java:100)
at jdk.nashorn.internal.runtime.linker.NashornLinker.getGuardedInvocation(NashornLinker.java:102)
at jdk.nashorn.internal.runtime.linker.NashornLinker.getGuardedInvocation(NashornLinker.java:94)
at jdk.internal.dynalink.support.CompositeTypeBasedGuardingDynamicLinker.getGuardedInvocation(CompositeTypeBasedGuardingDynamicLinker.java:176)
at jdk.internal.dynalink.support.CompositeGuardingDynamicLinker.getGuardedInvocation(CompositeGuardingDynamicLinker.java:124)
at jdk.internal.dynalink.support.LinkerServicesImpl.getGuardedInvocation(LinkerServicesImpl.java:149)
at jdk.internal.dynalink.DynamicLinker.relink(DynamicLinker.java:233)
at jdk.nashorn.internal.scripts.Script$\^eval\_.:program(<eval>:1)
at jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(ScriptFunctionData.java:636)
at jdk.nashorn.internal.runtime.ScriptFunction.invoke(ScriptFunction.java:229)
回答1:
The traceback contains the Nashorn eval
method, which means it is encountering an unhandled error while running the embedded JavaScript.
I think it's likely on the first line of the script: the methods called to instantiate your Java objects may not exist under the names used in the script.
The docs on this say to call Java.type
with a fully qualified Java class name, and then to call the returned function to instantiate a class from JavaScript. Try creating a circle in a smaller script that looks like:
var Circle = Java.type("mypackage.Circle");
var myCircle = new Circle();
// ...
and building up from there; be sure to replace mypackage
with the actual package name for this code.
来源:https://stackoverflow.com/questions/30156214/nashorn-typeerror-cannot-call-undefined-in-eval