The following code excerpts are problematic. For each one, explain what is wrong with the

code, which good practice was not applied and how you would improve the code.

a$)[3\%]$ Result r $=$ null;

if $($something$)$

r $=[..$some query..$]$;

try $\{$

r$.$method$()$;

$\}$

catch $($Exception e$)\{$

$\}$b$)[3\%]$ $q$1="$an SQL query";

$q$2=$ "another SQL query";

$...$

$qn $=$ "the nth SQL query";

$...$

for $($$i $=1$; $i $<9$; $i$++)\{$

$qi $="$q$i$"$;

$q $=$ $$qi;

query$($$q$)$;

$\}$

c$)[3\%]$ for $($int i $=0$; i $<3$; i$++)$

$\{$

switch $($i$)$

$\{$

case $0$:

DoThing$1()$;

break;

case $1$:

DoThing$2()$;

break;

case $2$:

DoThing$3()$;

break;

$\}$

$\}$

d$)[3\%]$ String result $=($ String $)$ aMap.get$($ key $)$;

if$($ result $==$ null $)$

$\{$

result $=$ null;

$\}$

return result;