java - Nested flatmap observable rxJava -

say have blog post api returns list<post> i'd translate else using rxjava. overall i'd break long string paragraphs , words, each word, combine paragraphs , combine blog post. each post can broken multiple paragraphs broken multiple words. logically i'd following , can't find async manner in.

• create observable list
• split each observable observable<string> on \n give me paragraphs
• split paragraphs observable<string> on ' ' segment words
• do kind of transformation each word (some words have puncuation part of them fine)
• combine words paragraph putting space between each one
• combine paragraphs post putting carriage return between each one.

i'm having trouble figuring out how multiple levels of splitting , combining on particular term. if needed split pages can flatmap(observable::from).tolist() won't seem work. appreciated.

i think should work fine, code pretty self-explanatory.

i make nested calls observable#from split posts paragraphs , paragraphs words. use observable#reduce concatenate words obtain single paragraph, , reduce again concatenate paragraphs single post.

observable<list<string>> blogpostswithreversedwords(list<string> blogposts) {     return observable.from(blogposts)             .flatmap(this::blogposttoparagraphs)             .tolist(); }  observable<string> blogposttoparagraphs(string post) {     return observable.from(post.split("\n"))             .flatmap(this::paragraphtowords)             .reduce((prevtext, nextparagraph) -> prevtext + "\n" + nextparagraph); }  observable<string> paragraphtowords(string paragraph) {     return observable.from(paragraph.split(" "))             .map(this::reverseword)             .reduce((prevtext, nextword) -> prevtext + "\n" + nextword); }  string reverseword(string word) {     return new stringbuilder(word).reverse().tostring(); }