You’ll need to do one of the following.
-
If it’s your code, then define your own functional interface that declares the checked exception:
@FunctionalInterface public interface CheckedFunction<T, R> { R apply(T t) throws IOException; }
and use it:
void foo (CheckedFunction f) { ... }
-
Otherwise, wrap
Integer myMethod(String s)
in a method that doesn’t declare a checked exception:public Integer myWrappedMethod(String s) { try { return myMethod(s); } catch(IOException e) { throw new UncheckedIOException(e); } }
and then:
Function<String, Integer> f = (String t) -> myWrappedMethod(t);
or:
Function<String, Integer> f = (String t) -> { try { return myMethod(t); } catch(IOException e) { throw new UncheckedIOException(e); } };