CODEWITHSUNDEEP
java
RyanS
RyanS

Reputation: 85

Easily pass values in a list as parameters to a method

Is there any easy way to pass all the values in a arbitrary length List as parameters to a method. In the following code, for example, I would want the params in method2 to be a sequence of the values residing in the params List (but without the List structure). Because the list is of arbitrary length, I can't just run through a loop and assign each value in the list to a variable, and then pass those variables to method2.

void method1( List<Double> params ){
    void method2(params...)
}

Thanks! ~ryan

Upvotes: 0

Views: 1168

Answers (3)

strikedaemon
strikedaemon

Reputation: 11

For method2 to be able to receive a variable number of arguments you need to declare it this way:

void method2(Double ... args)

In this case, args will be a Double[].

What you need to do in method1 is to convert your List to a Double[].

Here's a sample:

public static void main(String[] args) {

    List<Double> list = new ArrayList<Double>();

    list.add(1.0);
    list.add(2.0);
    list.add(3.0);

    method1(list);
}

public static void method1(List<Double> list) {
    method2(list.toArray(new Double[] {}));
}

public static void method2(Double... args) {

    for (int i = 0; i < args.length; i++) {
        System.out.println(args[i]);
    }
}

Hope this helps!

Upvotes: 1

Edwin Dalorzo
Edwin Dalorzo

Reputation: 78649

How about this way?

void method1(Double... params ){
    method2(Arrays.asList(params));
}

This would allow you to do things like

method1(1.0);
method1(1.0, 2.0);
method1(1.0, 2.0, 3.0);
method1(1.0, 2.0, 3.0, 4.0);

Upvotes: 0

Code-Apprentice
Code-Apprentice

Reputation: 83577

You can declare

public void method2(Double... doubles) {
}

See the Java varargs documentation for details.

Upvotes: 3

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