java 构造函数里面的Array-List作为参数之一，如何新建对象？
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Array-List inside constructor as one of the parameter, how to create a new object?
提问by fra pet
i am having problem with a constructor that takes an arrayList as one of the arguments.
我遇到了一个将 arrayList 作为参数之一的构造函数的问题。
public class ItemisedProductLine extends ProductLine{
public static ArrayList<String> serialNumbers;
public ItemisedProductLine(String productCode, double recRetPrice, double salePrice, int quantity, String description, ArrayList<String> SerialNumbers){
super( productCode, recRetPrice, salePrice, quantity, description);
this.serialNumbers = serialNumbers;
}
}
}
Now in my class Inventory i want to instantiate a new ItemisedProductLine and pass an arryList of serial number to the constructor
现在在我的类 Inventory 中，我想实例化一个新的 ItemisedProductLine 并将序列号的 arryList 传递给构造函数
ItemisedProductLine item = new ItemisedProductLine("productCode", 2600, 2490, 2, "descrpition", new ArrayList<String>("1233456", "6789123"));
Is this possible in Java? It seem to be not a common task to do, did not found any example.
这在Java中可能吗？这似乎不是一个常见的任务，没有找到任何例子。
As alternative i could have used an generic array instead of Array-List but then i can not initialize it because of the unknown size
作为替代方案，我可以使用通用数组而不是 Array-List 但由于未知大小，我无法初始化它
Let's hope i'm not forgetting another parenthesis :-)
让我们希望我不会忘记另一个括号:-)
Last Thing is the error is "no suitable constructor found ArraList<>"
最后一件事是错误是“找不到合适的构造函数ArraList<>”
回答by Edwin Dalorzo
You could try:
你可以试试：
new ArrayList<String>(Arrays.asList("1233456", "6789123"))
回答by Jake Biesinger
@Edwin's answer is good, but you could also ditch the ArrayListconstructor in favor of a simple cast. Arrays.asListalready creates a new ArrayListfor you.
@Edwin 的回答很好，但您也可以放弃ArrayList构造函数，转而使用简单的强制转换。Arrays.asList已经new ArrayList为您创建了一个。
(ArrayList<String>) Arrays.asList("1233456", "6789123")
(ArrayList<String>) Arrays.asList("1233456", "6789123")
回答by George Siggouroglou
There is another way using Java 8 Stream API.
You can create a Stream of objects and collect them as a List (or Set or whatever cause you can build your own collector).
还有另一种使用Java 8 Stream API 的方法。
您可以创建对象流并将它们收集为 List （或 Set 或任何您可以构建自己的收集器的原因）。
Stream.of(
new MyClassConstructor("supplierSerialNo", "supplierSerialNo", String.class),
new MyClassConstructor("title", "title", String.class),
new MyClassConstructor("kind", "kind", String.class))
.collect(Collectors.toList())
