Suppose $\mathbb{Z} \overset{1}\longrightarrow \mathbb{Z} \overset{2}\longrightarrow \mathbb{Z} \overset{3}\longrightarrow \mathbb{Z} \overset{4}\longrightarrow\mathbb{Z}\longrightarrow\cdots$.
How to compute the direct limit of above groups?Does there exist a general method to calculate the direct limit of groups?