Question

这是Groovy的人们的错误还是故意的设计决定？

final String x = "a"
x = "b"

你运行它，它会工作，没问题。不应该抛出运行时异常吗？用@CompileStatic注释班级也没有帮助。我在使用@CompileStatic时期待编译错误。

Answer 1

如果将其编译为Script，groovyc将忽略final关键字，但如果将其包装到类中，groovyc将引发编译错误

fin.groovy with content

final String x = "a"
x = "b"

$ groovyc fin.groovy

使用ByteCodeViewer

进行反编译

import org.codehaus.groovy.reflection.*;
import java.lang.ref.*;
import groovy.lang.*;
import org.codehaus.groovy.runtime.*;
import org.codehaus.groovy.runtime.callsite.*;

public class fin extends Script
{
    private static /* synthetic */ SoftReference $callSiteArray;

    public fin() {
        $getCallSiteArray();
    }

    public fin(final Binding context) {
        $getCallSiteArray();
        super(context);
    }

    public static void main(final String... args) {
        $getCallSiteArray()[0].call((Object)InvokerHelper.class, (Object)fin.class, (Object)args);
    }

    public Object run() {
        $getCallSiteArray();
        String x = "a";
        return x = "b";
    }

    private static /* synthetic */ CallSiteArray $createCallSiteArray() {
        final String[] array = { null };
        $createCallSiteArray_1(array);
        return new CallSiteArray((Class)fin.class, array);
    }

    private static /* synthetic */ CallSite[] $getCallSiteArray() {
        CallSiteArray $createCallSiteArray;
        if (fin.$callSiteArray == null || ($createCallSiteArray = fin.$callSiteArray.get()) == null) {
            $createCallSiteArray = $createCallSiteArray();
            fin.$callSiteArray = new SoftReference($createCallSiteArray);
        }
        return $createCallSiteArray.array;
    }
}

没有final了，如果你用内容编译它

class A{
    final String x = "a"
    def a(){
        x = "b"
    }
}

它给出了

$ groovyc fin.groovy 
org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
fin.groovy: 4: cannot modify final field 'x' outside of constructor.
 @ line 4, column 3.
   x = "b"
   ^

1 error

＆＃39;最终＆＃39; Groovy中的关键字

1 个答案: