how to convert two similar methods in one?

Question

How can I make one method generic method doRetry out of these two methods doRetryA and doRetryB in Java where moth boths execute similar code but differs in func1 and func2 calls where func1 and func2 take same number of arguments and these arguments are same types but func1 and func2 differs in functionalities but return same type?

SomeType foo = someEnum.enumValue;


private SomeType def doRetryA() {
    for(int attempt=0; attempt<retries; attempt++) {
        foo = func1(a, b);
    return foo;
}

private SomeType def doRetryB() {
    for(int attempt=0; attempt<retries; attempt++) {
        foo = func2(a, b);
    return foo;
}

Just take the function as an argument, a bi-function would do it. — Ravindra Ranwala, Sep 21 '21 at 10:03
`doRetry(BiFunction func) { ... foo = func.apply(a, b); ... }`. Then you can call it as `doRetry(this::func1);` or `doRetry(this::func2);` — QBrute, Sep 21 '21 at 10:05
func1 and func2 both throws IOException, InterruptedException and now doRetry complains about unhandled exceptions. — Dariusz Krynicki, Sep 21 '21 at 10:19
@darkman define `interface ThrowingBiFunction`, which has a single method that is declared to throw the checked exceptions. — Andy Turner, Sep 21 '21 at 10:24
You didn't specify that so we couldn't know. That's why it's important to include all important information in your question — QBrute, Sep 21 '21 at 10:24
I realize and agree with you. BiFunction helps here but I did not know throwing exeption is important part here. — Dariusz Krynicki, Sep 21 '21 at 10:25
@AndyTurner how could I use this interface ThrowingBiFunction? I am not Java native. — Dariusz Krynicki, Sep 21 '21 at 10:26
Does this answer your question? [Java: how to handle retries without copy-paste code?](https://stackoverflow.com/questions/9539845/java-how-to-handle-retries-without-copy-paste-code) — Joe, Sep 21 '21 at 10:30
nah, I am using java 11 HttpClient and manualy solving retries with simple for loop — Dariusz Krynicki, Sep 21 '21 at 10:36

score 0 · Answer 1 · answered Sep 21 '21 at 10:49

Define an interface like so:

interface ThrowingBiFunction<A, B, C> {
  C apply(A a, B b) throws IOException, InterruptedException;
}

then accept an instance of this in your method:

private FooType doRetry(ThrowingBiFunction<AType, BType, FooType> func) {
    for(int attempt=0; attempt<retries; attempt++) {
        foo = func.apply(a, b);
    return foo;
}

I don't know the types of a, b or foo. Perhaps they are the same in both cases, perhaps they're not. If they're not the same, add some type parameters, e.g.

private <AType, BType, FooType> FooType doRetry(ThrowingBiFunction<AType, BType, FooType> func) {

Then invoke:

doRetry((a, b) -> func1(a, b));  // Or doRetry(this::func1) or similar.
doRetry((a, b) -> func2(a, b));

score 0 · Answer 2 · answered Sep 21 '21 at 16:40

you can pass the function type you want using a string variable as something like this...

SomeType foo = someEnum.enumValue;

private SomeType def doRetry(String funcType) {
    for (int attempt=0; attempt<retries; attempt++) {
        if (funcType.equals("ONE")) {
            foo = func1(a, b);
        } else if (funcType.equals("TWO")) {
            foo = func2(a, b);
        }
    }
    return foo;
}

//function call
doRetry("ONE");

how to convert two similar methods in one?

2 Answers2