loops - 在 groovy 中迭代 Map, Map>

Question

嗨，我有复杂的结构

 Map<Map<String,String>, Map<String,String>> a

我想遍历它的所有元素。我试过:

for(Map.Entry<Map<String,String>, Map<String,String>> first:firstMap.keySet()) { 
...
}

错误是

Cannot cast object '{key1=value1, key2=value2, key3=value3, key4=value4}' with class 'java.util.LinkedHashMap' to class 'java.util.Map$Entry' due to: groovy.lang.GroovyRuntimeException: Could not find matching constructor for: java.util.Map$Entry(java.util.LinkedHashMap)

如何迭代我的 map ？

Answer 1

keySet()只返回它的键，所以它是一个 Map<String, String> 的列表.如果你想遍历它的 Map.Entry ，放下 .keySet() :

for (Map.Entry<Map<String, String>, Map<String, String>> entry : firstMap) {
  println "entry=$entry"
}

其他循环选项:

// iterate with two arguments
firstMap.each { Map<String, String> key, Map<String, String> value ->
  println "key=$key, value=$value"
}

// iterate through entries
firstMap.each { Map.Entry<Map<String, String>, Map<String, String>> entry ->
  println "entry=$entry"
}

// untyped
for (entry in firstMap) {
  println entry
}