Rolling up pants is continuous trend from Spring. In Tokyo, humidity level is high, so I can see people roll up their bottom every year. The difference of this trend between this year and other years is how long they roll up their bottom. Most people roll up their bottom around the top of their ankle. Rolling up at below the knees is too much in this summer.
Regarding shoes they choose, they pick flip-flop, leather sandal, slip-on shoes and, off course, sneaker. My favorite combination is slim jeans and high-cut basketball shoes. I used to see lapping jeans bottom on a basketball shoes, but everybody rolls up bottom and give a glimpse of their ankles in this summer. Here are other rolled up pants styles.
Shorts is also a trend item among mens. The length should be over knees. I saw some guys roll up the shorts to adjust the length. I guess this style is derived from ivy look boom men's magazines boosted up, so the guys usually wear jacket or polo shirt along with leather shoes.
Here is good shorts style.
There are other shorts styles with sneakers, which are more casual.
In this summer, don't forget show your ankles or knees whenever you wear pants :)