java - 将省略号作为参数传递给 java 方法

Question

我有一个 Java 方法，它接受省略号格式的参数。该方法依次调用一个 api，该 api 再次接受省略号格式的参数:

public void myMethod(String a, String... listOfParam){

   //Method Signature of anotherAPI is anotherAPI(String input, Object ... listOfParams)

   //I call anotherAPI method as described below.
   String result = anotherAPI(a, listOfParam); 
}

但是，当我将 listOfParams 作为参数传递时，我得到 UnsupportedOperationException。

请让我知道这种情况下的正确方法。

编辑

我正在调用 AmazonDynamoDB Java API( http://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/index.html?index-all.html ) addHashOnlyPrimaryKeys 方法:

客户端方法如下:

public static List<Item> getAllItems(String tableName,String primaryKeyName, String ... listOfKeys){
    List<Item> itemList = null;
    System.out.println(listOfKeys.toString());
    TableKeysAndAttributes tkaa = new TableKeysAndAttributes(tableName);
    tkaa.addHashOnlyPrimaryKey(primaryKeyName, listOfKeys);
    BatchGetItemOutcome outcome = dynamoDB.batchGetItem(tkaa);
    itemList = outcome.getTableItems().get(tableName);
    return itemList;
}

我测试此方法为:

List<Item> listOfItems = AmazonDynamoDBUtil.getAllItems("myTable","data","1","2","3","4");

这里的数据是字符串类型。

但是，我得到的异常(exception)是:

Exception in thread "main" java.lang.UnsupportedOperationException: value type: class [Ljava.lang.String;
        at com.amazonaws.services.dynamodbv2.document.internal.InternalUtils.toAttributeValue(InternalUtils.java:221)
        at com.amazonaws.services.dynamodbv2.document.internal.InternalUtils.toAttributeValueMap(InternalUtils.java:535)
        at com.amazonaws.services.dynamodbv2.document.internal.InternalUtils.toAttributeValueMap(InternalUtils.java:547)
        at com.amazonaws.services.dynamodbv2.document.internal.BatchGetItemImpl.doBatchGetItem(BatchGetItemImpl.java:84)
        at com.amazonaws.services.dynamodbv2.document.internal.BatchGetItemImpl.batchGetItem(BatchGetItemImpl.java:58)
        at com.amazonaws.services.dynamodbv2.document.DynamoDB.batchGetItem(DynamoDB.java:154)
        at awsdynamodb.AmazonDynamoDBUtil.getAllItems(AmazonDynamoDBUtil.java:63)

请让我知道这种方法可能存在什么问题。

Answer 1

这正在工作:

public class Main {

    public static void main(String[] args) {
        myMethod("test 1");
        myMethod("test 2", "a");
        myMethod("test 3", "a", "b", "c");
    }

    public static void myMethod(String a, String... listOfParam) {
        anotherAPI(a, listOfParam);
    }

    private static void anotherAPI(String a, String... listOfParam) {
        StringBuilder sb = new StringBuilder();
        for (String p : listOfParam) {
            sb.append(p);
            sb.append(", ");
        }
        System.out.println(a + ": " + sb.toString());
    }
}

产生预期结果:

test 1: 
test 2: a, 
test 3: a, b, c, 

从 Java 的角度来看，listOfParam 作为 String... 是一个 String[] 数组。