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Java for Loop evaluation
(9 answers)
JVM option to optimize loop statements
(4 answers)
Closed 3 years ago.
if I have the following code:
int p=something
int l=somethingelse
int sum=0;
for(int i=0;i<p-l;i++)
sum+=(~i)^2+1337
can I generally assume the compiler optimizes the code so that p-l aren't recalculated every loop and is just cached since neither is changed in the loop? Or do I have to put p-l into a seperate variable if I want optimal performance?
Related
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When to use wrapper class and primitive type
(11 answers)
What is the difference between Integer and int in Java?
(11 answers)
Closed 1 year ago.
This post was edited and submitted for review 1 year ago and failed to reopen the post:
Original close reason(s) were not resolved
I know that Integer is a class and int is just a number, but when should we use one over another and how to convert Integer to int (and vice versa)?
** Also, there is this
question (what is autoboxing by the way) but I am asking WHEN to use int over Integer in actual programming (such as performance issues, ease of use and readability) and vice versa and not the DIFFERENCE between them.
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Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop
(31 answers)
ArrayList filter [duplicate]
(6 answers)
Closed 5 years ago.
I want to remove some objects (if they meet a condition) of an ArrayList while looping through it. But that will obviously throw a 'ConcurrentModificationException'.
So, what's the best way of doing this?
edit: My condition is a number comparision, so if an objects' variable is greater than a value, the object must be removed from the list..
In Java 8:
rooms.removeIf(r -> r.getSize() >= 40) ;
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Is there a way to access an iteration-counter in Java's for-each loop?
(16 answers)
Closed 5 years ago.
Can we know the count of the iteration (that is whether it's the first, second, third ... iteration ) while we are stepping over the code in a for each loop, in the eclipse debugger? Eclipse must be holding a count but how to get it show it to us. Apart from the workarounds of introducing an index in the code can we utilize something in built in eclipse.
You can initiate a counter and increment it in the for loop, it should be a workaround.
You can track the variable under Eclipse console below:
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Which is better: letting Java do autoboxing or using valueOf()
(3 answers)
Closed 6 years ago.
Integer x = 5;
Integer x = Integer.valueOf(5);
Is there any scenario where I would want to use the 2nd one specifically or is it redundant altogether and shouldn't not bother about it?
After Java 5 (because of autoboxing / unboxing) there is no difference except the first one is shorter.
Both statements are equivalent.
The statement Integer x = 5 would be compiled to
Integer x = Integer.valueOf(5);
The compiler will do that for you behind the scene, so the only difference is the number of character in source file.
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How do I compare strings in Java?
(23 answers)
Closed 7 years ago.
String TypedMaxNumber = MaxValue.getText();
if(TypedMaxNumber == "100")
System.out.println(TypedMaxNumber+" = 100");
I think it is a silly problem, but when I am running to run this program and I type 100 in the text Field it is not going inside the loop. What could be the reason.
I am running to run this program and I type 100 in the text Field it
is not going inside the loop.
Its
if(TypedMaxNumber.equals("100"))
Since TypedMaxNumber is of type String. equals() check for value equality