Java - 使用for循环创建数组

Question

Is it possible in Java to make an array in a style similar to this, i have been searching for a while and haven't found anything.

int[] foo = {
    for(String arg:args)
        return Integer.parseInt(arg);
};

Answer 1

No, but you can do this instead :

int[] foo = new int[args.length];
for(int i = 0; i < foo.length; i++) {
    foo[i] = Integer.parseInt(args[i]);
}

Answer 2

Not exactly, but try this.

int[] foo = new int[args.length]; //Allocate the memory for foo first.
for (int i = 0; i < args.length; ++i)
    foo[i] = Integer.parseInt(args[i]);
//One by one parse each element of the array.

Answer 3

使用Java 8，它可以这样做：

int[] foo = Stream.of(args).mapToInt(str -> Integer.parseInt(str)).toArray();

Answer 4

Kind of... Since Java 8 we have streams which can simulate loop and allow us to do things like

int[] arr = Arrays.stream(args).mapToInt(s -> Integer.parseInt(s)).toArray();

or its equivalent using method references

int[] arr = Arrays.stream(args).mapToInt(Integer::parseInt).toArray();

Answer 5

int[] foo = new int[arg.length];
for (int i =0;i<args.length;i++) foo[i]=Integer.parseInt(args[i]);

Answer 6

With array no, but you can do something similar with List :

final String args[] = {"123", "456", "789"};

List<Integer> list = new LinkedList<Integer>(){
    {
        for (String arg: args){
            add(Integer.parseInt(arg));
        }
    }
};

System.out.println(list); // [123, 456, 789]

With array you have to do the following:

int[] foo = new int[args.length];
for (int i = 0; i < foo.length; i ++) {
    foo[i] = Integer.parseInt(args[i]);
}