The difference between thenapply () and Thencompose ()

The difference between thenapply () and Thencompose ():

Thenapply () is a non-completablefuture type returned:
its function is equivalent to converting completablefuture<t> into completablefuture<u>.

Thencompose () is used to connect two completablefuture, and the return value is the new completablefuture:

Summary: thenapply () conversion is the type of the generic, is the same completablefuture;
Thencompose () is used to connect two completablefuture and is to generate a new completablefuture.

Example:
1.thenApply ():

completablefuture<integer> future = Completablefuture.supplyasync ((), {

return 100;

});

completablefuture<string> f = future.thenapplyasync (i-i). thenapply (i-i.tostring ());

System.out.println (F.get ()); "1000"

Thenapply () Source code:

Public <U> completablefuture<u> Thenapply (
function<? Super T,? Extends u> fn) {
return uniapplystage (NULL, FN);
}

Interpretation:
Parameters: function<? Super T,? Extends u> fn)
Enter the value of T in the preceding completablefuture<t>, return the value of the type that inherits U, return this value

Order: First determine the return value U or its subclass, and then determine the <U> type in the method in public <U> completablefuture<u> thenapply ()

2.thenCompose ():

completablefuture<integer> future = Completablefuture.supplyasync ((), {

return 100;

});

completablefuture<string> f = future.thencompose (I, {

Return Completablefuture.supplyasync ((), {

Return (I * 10) + "";

});

});

System.out.println (F.get ()); 1000

The difference between thenapply () and Thencompose ()