java中带有可变数量参数的字符串格式

Question

考虑一个字符串.

String Str = "Entered number = %d and string = %s"

让我们说我有一个对象列表

List<Objects> args = new ArrayList<Objects>();
args.add(1);
args.add("abcd");

有什么方法可以将这些args替换成Str,这样我就能获得一个像"Entered number = 1 and string = abcd "？

通过概括,我计划将所有问题和参数转储到文件(如json)中,并在运行时执行它们.如果有更好的方法,请告诉我.

Answer 1

尝试:

String formatted = String.format(str, args.toArray());

这给出了:

Entered number = 1 and string = abcd

Answer 2

您可以使用以下内容:

String str = "Entered number = %d and string = %s";

List<Object> args = new ArrayList<Object>();
args.add(1);
args.add("abcd");

System.out.println(String.format(str, args.toArray()));

会给出输出:

Entered number = 1 and string = abcd

来自JLS 8.4.1格式参数:

The last formal parameter in a list is special; 
it may be a variable arity parameter, indicated by an 
elipsis following the type.

If the last formal parameter is a variable arity parameter of type T, 
it is considered to define a formal parameter of type T[]. 
The method is then a variable arity method. Otherwise, it is a fixed arity 
method. Invocations of a variable arity method may contain more actual 
argument expressions than formal parameters. All the actual argument 
expressions that do not correspond to the formal parameters preceding 
the variable arity parameter will be evaluated and the results stored 
into an array that will be passed to the method invocation.

在StackOverflow上看到这个问题!