Optional method parameter in Java

Question

I have this function httpGet() which calls http():

public static int httpGet(String url, StringBuilder response) throws IOException {
    return http(url,(http)->http.setRequestMethod("GET"), response);
}

private static int http(String url, httpMethod method, StringBuilder response) throws IOException {
    HttpURLConnection http = (HttpURLConnection)new URL(url).openConnection();
    http.setConnectTimeout(5000);
    http.setReadTimeout(5000);
    method.doMethod(http);
    int status = 404;
    ......
    ......
    return status;
}

I want to add an additional parameter for readTimeout, which needs to be optional with a default value that will be used otherwise.

In this case readTimeout is set to 5000 for all the calls, but I want this specific call to be executed for longer timeouts.

I think I need this new parameter to be optional as I don't want to change the implementations where this http() method has been called.

This is how I call it:

Assert.assertEquals(HTTP_OK, httpGet(DEFAULT_BROWSCAP_ENDPOINT, result));

How can I implement a new optional parameter for readTimeout?

Java doesn't have default values like Python, C++, VBA, Delphi, and many languages. Create new constructors with the alternate signature. — IceArdor
– IceArdor, Commented Aug 27, 2015 at 8:21
You need to define a new method, (unfortunately?) java doesn't support optional parameters. — BackSlash
– BackSlash, Commented Aug 27, 2015 at 8:22

IceArdor · Accepted Answer · 2015-08-27 08:29:25Z

2

Java doesn't have default values like Python, C++, VBA, Delphi, and many languages. Create new constructors with the alternate signature.

public static int httpGet(String url, StringBuilder response) throws IOException {
    return httpGet(URL, response, 5000)
}

public static int httpGet(String url, StringBuilder response, int readTimeout) throws IOException {
    return http(url,(http)->http.setRequestMethod("GET"), response, readTimeout);
}


private static int http(String url, httpMethod method, StringBuilder response) throws IOException {
    return http(url, method, response, 5000);
}

private static int http(String url, httpMethod method, StringBuilder response, int readTimeout) throws IOException {
    HttpURLConnection http = (HttpURLConnection)new URL(url).openConnection();
    http.setConnectTimeout(5000);
    http.setReadTimeout(readTimeout;
    method.doMethod(http);
    int status = 404;
    ......
    ......
    return status;
}

answered Aug 27, 2015 at 8:29

IceArdor

2,05122 silver badges20 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

sdabet Over a year ago

I think there's no need to create two versions of the private http() method, right?

IceArdor Over a year ago

No need in having an unused constructor. I didn't know if there was other code that was dependent on the shorter constructor.

sdabet · Accepted Answer · 2015-08-27 08:58:01Z

You need to create 2 versions of the httpGet method (one with the readTimeout parameter, and another one without it which will call the first version with a default value):

private static final long DEFAULT_READ_TIMEOUT = 5000;

public static int httpGet(String url, StringBuilder response) throws IOException {
    return httpGet(url, response, DEFAULT_READ_TIMEOUT);
}

public static int httpGet(String url, StringBuilder response, long readTimeout) throws IOException {
    return http(url,(http)->http.setRequestMethod("GET"), response, readTimeout);
}

private static int http(String url, httpMethod method, StringBuilder response, long readTimeout) throws IOException {
    HttpURLConnection http = (HttpURLConnection)new URL(url).openConnection();
    http.setConnectTimeout(5000);
    http.setReadTimeout(readTimeout);
    method.doMethod(http);
    int status = 404;
    ......
    ......
    return status;
}

Now you can decide to provide the timeout

httpGet(DEFAULT_BROWSCAP_ENDPOINT, result, mytimeout)

or not

httpGet(DEFAULT_BROWSCAP_ENDPOINT, result)

Parker Hoyes · Accepted Answer · 2015-08-27 08:22:09Z

Generally the way this is done is by providing many different functions with different signatures that just assume a default value. This can be done by "chaining" a bunch of functions together, each specifying it's default value and calling the more detailed function. For example:

public void myFunctionWithALotOfArguments(int a, int b, int c, int d) {
    // do stuff
}
public void myFunctionWithLessArguments(int a, int b, int c) {
    myFunctionWithALotOfArguments(a, b, c, 50);
}
public void myFunctionWithFewArguments(int a, int b) {
    myFunctionWithLessArguments(a, b, 25);
}
public void mySimplifiedFunction(int a) {
    myFunctionWithFewArguments(a, 9);
}
public void justGuessWhatToDo() {
    mySimplifiedFunction(42);
}

Collectives™ on Stack Overflow

Optional method parameter in Java

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related