将变量值保存在变量中而不是多次调用是否更好？

Question

I have Item item; which has getName() getter. I need to acces item.getName() in some loop. Is it better to call item.getName() in loop each time, or save it in additional variable and use that variable and is there difference?

For example: Item item;

String itemName=item.getName();

for(int i=0;  i< itemArray.size();i++){

    itemArray.get(i).setName(itemName);
}

or

for(int i=0; i< itemArray.size();i++){

    itemArray.get(i).setName(item.getName());
}

Answer 1

If you're gonna re-assign item over and over again in your loop, then you need to use item.getName() , else you can just store the value in a local variable, and use that in the loop. And if you're not gonna change its value, then you can make it final too.

Eg:

final String name = item.getName();
while(comdition){ // some loop
    // something involving name. But not modifying it.
}

Answer 2

When you use item.getName() you will get always the current fresh value. Saving it into an additional variable while iterating over it may will not see changes. If this is your intent its ok and declare it as final as it will be thread-safe. Otherwise I don´t think this will be a big performance issue. Keep using the getter.

Answer 3

Which one would you prefeer?

String itemName;

for(int i=0;i<itemArray.size();i++){
   itemName=itemArray.get(i).getName();
   System.out.println(itemName);
}

or

for(int i=0;i<itemArray.size();i++){
   System.out.println(itemArray.get(i).getName);
}