#Variable Names
Your variables names are unnecessarily abbreviated and genetic. Also suffixes such as Arr are usually unnecessary. Here some example I'd use:
str=>sentencestrArr=>wordsstrTemp=>word
#Algorithm
You could drop copying the strings into the character array, by using strArr directly and simply checking if j exceeds the length of the word and printing a space if it does.
Also getting the maximal word length could also be avoided, if you check during output, iff all strings are shorter than j.