To reproduce:

$ emacs -q

Type the following in a Java buffer:

class X
{
    String field1;
    String[] field2;
    int field3;
    int[] field4;
    X field5;
    X[] field6;
}

Select the six field lines and 'M-x align' them:

class X
{
    String    field1;
    String[] field2;
    int        field3;
    int[] field4;
    X        field5;
    X[] field6;
}

Expected result:

class X
{
    String    field1;
    String[]    field2;
    int        field3;
    int[]    field4;
    X        field5;
    X[]        field6;
}

Emacs version (just compiled trunk): GNU Emacs 25.0.50.1
(x86_64-unknown-linux-gnu, GTK+ Version 3.10.9) of 2014-12-15