[英]How to call a varargs method with an additional argument from a varargs method
I have some varargs system function, where T is some actual type, like String
: 我有一些varargs系统函数,其中T是一些实际类型,如
String
:
sys(T... args)
I want to create own function, which delegates to the system function. 我想创建自己的函数,它委托给系统函数。 My function is also a varargs function.
我的功能也是一个varargs功能。 I want to pass through all the arguments for my function through to the system function, plus an additional trailing argument.
我想通过系统函数传递函数的所有参数,以及一个额外的尾随参数。 Something like this:
像这样的东西:
myfunc(T... args) {
T myobj = new T();
sys(args, myobj); // <- of course, here error.
}
How do I need to change the line with the error? 如何更改错误行? Now I see only one way: create array with dimension [args] + 1 and copy all items to the new array.
现在我只看到一种方法:创建维度[args] + 1的数组,并将所有项目复制到新数组。 But maybe there exists a more simple way?
但也许存在一种更简单的方法?
Now I see only one way: create array with dimension [args] + 1 and copy all items to new array.
现在我只看到一种方法:创建维度[args] + 1的数组并将所有项目复制到新数组。
There is no simpler way. 没有更简单的方法。 You need to create a new array and include
myobj
as last element of the array. 您需要创建一个新数组并将
myobj
包含为数组的最后一个元素。
String[] args2 = Arrays.copyOf(args, args.length + 1);
args2[args2.length-1] = myobj;
sys(args2);
If you happen to depend on Apache Commons Lang you can do 如果您碰巧依赖Apache Commons Lang,您可以这样做
sys(ArrayUtils.add(args, myobj));
or Guava 或番石榴
sys(ObjectArrays.concat(args, myobj));
You may call sys()
twice if the order doesn't care: 如果订单不关心,您可以调用两次
sys()
:
T myobj=new T();
sys(myobj);
sys(args);
If you can't use this, switch to collections (eg. LinkedList) for all of your functions. 如果您不能使用它,请切换到所有功能的集合(例如LinkedList)。
如果你可以使用番石榴 ,那么你可以这样做:
sys(ObjectArrays.concat(myobj, args))
Java 8解决方案:
sys(Stream.concat(Arrays.stream(args), Stream.of(myobj)).toArray(T[]::new));
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