groovy - 这个Groovy表达式有什么问题？

Question

通过GroovyShell(解释器)运行以下Groovy表达式:

if(fizz.subtype == null) {
    if(fizz.color == 'RED') fizz.subtype = "DOG";
    else if(fizz.color == 'BLUE') fizz.subtype = "CAT";
    else if(fizz.color == 'GREEN') fizz.subtype = "SHEEP";
    else if(fizz.color == 'ORANGE') fizz.subtype = "LION";
    else if(fizz.color == 'YELLOW') fizz.subtype = "SNAIL";
    else if(fizz.color == 'GRAY') fizz.subtype = "SHARK";
    else if(fizz.color == 'PURPLE') fizz.subtype = "BAT";
    else if(fizz.color == 'BLACK') fizz.subtype = "FOX";
}; fizz;

给我以下堆栈跟踪:

groovy.lang.MissingPropertyException: No such property: subtype for class: com.me.myapp.Fizz
    at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:50)
    at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.getProperty(ScriptBytecodeAdapter.java:479)
    at Script1.run(Script1.groovy:1)
    at groovy.lang.GroovyShell.evaluate(GroovyShell.java:543)
    at groovy.lang.GroovyShell.evaluate(GroovyShell.java:518)
    at com.tms.evaluator.GroovyEvaluator._evaluate(GroovyEvaluator.java:51)
    ...rest of stacktrace omitted for brevity

有任何想法吗？提前致谢!

Answer 1

您在if表达式的右括号后缺少分号:

fizz = [:]
if(fizz.subtype == null) {
    if(fizz.color == 'RED') fizz.subtype = "DOG";
    else if(fizz.color == 'BLUE') fizz.subtype = "CAT";
    else if(fizz.color == 'GREEN') fizz.subtype = "SHEEP";
    else if(fizz.color == 'ORANGE') fizz.subtype = "LION";
    else if(fizz.color == 'YELLOW') fizz.subtype = "SNAIL";
    else if(fizz.color == 'GRAY') fizz.subtype = "SHARK";
    else if(fizz.color == 'PURPLE') fizz.subtype = "BAT";
    else if(fizz.color == 'BLACK') fizz.subtype = "FOX";
}; fizz;

另外，我可以建议使用 map 进行此类数据匹配吗？

fizz.color = 'ORANGE'

fizz.subtype = [
    'RED'    : 'DOG',
    'BLUE'   : "CAT",
    'GREEN'  : "SHEEP",
    'ORANGE' : "LION",
    'YELLOW' : "SNAIL",
    'GRAY'   : "SHARK",
    'PURPLE' : "BAT",
    'BLACK'  : "FOX"
][fizz.color]

assert fizz.subtype == 'LION'

case-match也可以工作，但是如果您有更复杂的任务，则最适合:

fizz.color = 'BLUE'

fizz.subtype = fizz.color.case {
    when 'RED'    then 'DOG'
    when 'BLUE'   then "CAT"
    when 'GREEN'  then "SHEEP"
    when 'ORANGE' then "LION"
    when 'YELLOW' then "SNAIL"
    when 'GRAY'   then "SHARK"
    when 'PURPLE' then "BAT"
    when 'BLACK'  then "FOX"
}

assert fizz.subtype == 'CAT'