Method swap

chapter18/src/main/java/com/seaofnodes/simple/Ary.java:106–113

( int i, int j )

    }

    public void swap( int i, int j ) {
        range_check(i);
        range_check(j);
        if( i==j ) return;
        E tmp = _es[i];
        _es[i] = _es[j];
        _es[j] = tmp;
    }


    /** @param c Collection to be added */