| Do not create any static variables unless explicitly allowed by the assignment. |
Instance variables must not be substitutes for parameters or local variables. [INSTANCE-VARIABLE: 2-20]
| An instance variable should be used to remember a property of an object, and must have a meaning between method calls. If you create an instance variable, ask yourself what property of the object it stores. Do not use an instance variable as a local variable or as a way to avoid passing a parameter. |
Do not change the same variable twice in one statement [DOUBLE-CHANGE: 1-2 points]
Do not write a statement that includes two explicit changes
of a variable. For example, statement
x = x++;tries to change x twice. |
Do not make a change that will surely not be seen [INVISIBLE-CHANGE: 1 point]
Do not use ++x where you really mean x+1. Do not
change the value of a local variable when the changed value
cannot possibly be looked at again. For example, do
not write
return test(++x);since the altered value of x cannot possibly be looked at. Instead, write return test(x+1); |
Do not store a value into a local variable just to return it [RETURN-VARIABLE: 1 pt]
If y is a local variable, do not write
return y = x + 1;which stores the value of x + 1 into variable y, and then immediately returns that value. There is no point to variable y. Just write return x + 1; |
Do not change the value of a parameter. [CHANGE-PARAM: 1-5 points]
Do not change the value of that parameter anywhere in the method
body. For example, method next defined by
static int next(int n)
{
while(!isgood(n))
{
n++;
}
return n;
}
takes parameter n. It changes the value of n
in the method body. Do not do that.
|