Do While Loops Versus For Loops in Java for Counting

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6
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Ok so this is a question that has probably been asked a thousand times, but none of them that I found really had an answer that I was particularly looking for. I have done much research on this topic but to no avail. My question is: When it comes to counting, should a do-while loop be used, or a for loop? Because this:

class Main 
 public static void main(String args) 
 int times = 1;
 do 
 System.out.println("I have printed " + times + " times.");
 times++;
 while (times < 6);

Seems to do the exact same thing as this:

class Main 
 public static void main(String args) 
 for (int times = 0; times < 6; times++) 
 System.out.println("I have printed " + times + " times.");

Is it a difference in speed? Preference? Situation? Personal quirks? Some kind of "Java social taboo"? I have no idea. Either seem to be able to be used for effective counting, just that one takes a lot more. And both print the exact same thing.

Sorry if this question isn't written very well, this is the first question I have asked on this site.

Thanks!!

edited 3 hours ago

asked 3 hours ago

Domani Tomlindo

313

New contributor

To an extent, it comes down to taste. I would prefer to use a for loop in this situtation, because the declaration is scoped to the loop, and incrementing is outside the loop body. The main difference between the types of loop, however, is that a do/while loop executes at least once, whereas a for (or a while) may not execute.
â€“Â Andy Turner
3 hours ago

It doesn't matter. BTW, with Java 8+, you can also do IntStream.rangeClosed(1, 6).forEach(times -> System.out.println("I have printed " + times + " times."));
â€“Â David Conrad
3 hours ago

add a commentÂ |Â

up vote
6
down vote

favorite

class Main 
 public static void main(String args) 
 int times = 1;
 do 
 System.out.println("I have printed " + times + " times.");
 times++;
 while (times < 6);

Seems to do the exact same thing as this:

class Main 
 public static void main(String args) 
 for (int times = 0; times < 6; times++) 
 System.out.println("I have printed " + times + " times.");

Sorry if this question isn't written very well, this is the first question I have asked on this site.

Thanks!!

edited 3 hours ago

asked 3 hours ago

Domani Tomlindo

313

New contributor

To an extent, it comes down to taste. I would prefer to use a for loop in this situtation, because the declaration is scoped to the loop, and incrementing is outside the loop body. The main difference between the types of loop, however, is that a do/while loop executes at least once, whereas a for (or a while) may not execute.
â€“Â Andy Turner
3 hours ago

It doesn't matter. BTW, with Java 8+, you can also do IntStream.rangeClosed(1, 6).forEach(times -> System.out.println("I have printed " + times + " times."));
â€“Â David Conrad
3 hours ago

add a commentÂ |Â

up vote
6
down vote

favorite

class Main 
 public static void main(String args) 
 int times = 1;
 do 
 System.out.println("I have printed " + times + " times.");
 times++;
 while (times < 6);

Seems to do the exact same thing as this:

class Main 
 public static void main(String args) 
 for (int times = 0; times < 6; times++) 
 System.out.println("I have printed " + times + " times.");

Sorry if this question isn't written very well, this is the first question I have asked on this site.

Thanks!!

edited 3 hours ago

asked 3 hours ago

Domani Tomlindo

313

New contributor

class Main 
 public static void main(String args) 
 int times = 1;
 do 
 System.out.println("I have printed " + times + " times.");
 times++;
 while (times < 6);

Seems to do the exact same thing as this:

class Main 
 public static void main(String args) 
 for (int times = 0; times < 6; times++) 
 System.out.println("I have printed " + times + " times.");

Sorry if this question isn't written very well, this is the first question I have asked on this site.

Thanks!!

java for-loop do-while counting

edited 3 hours ago

asked 3 hours ago

Domani Tomlindo

313

New contributor

edited 3 hours ago

asked 3 hours ago

Domani Tomlindo

313

New contributor

edited 3 hours ago

asked 3 hours ago

Domani Tomlindo

313

New contributor

asked 3 hours ago

Domani Tomlindo

313

asked 3 hours ago

Domani Tomlindo

313

New contributor

Domani Tomlindo is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

To an extent, it comes down to taste. I would prefer to use a for loop in this situtation, because the declaration is scoped to the loop, and incrementing is outside the loop body. The main difference between the types of loop, however, is that a do/while loop executes at least once, whereas a for (or a while) may not execute.
â€“Â Andy Turner
3 hours ago

It doesn't matter. BTW, with Java 8+, you can also do IntStream.rangeClosed(1, 6).forEach(times -> System.out.println("I have printed " + times + " times."));
â€“Â David Conrad
3 hours ago

add a commentÂ |Â

To an extent, it comes down to taste. I would prefer to use a for loop in this situtation, because the declaration is scoped to the loop, and incrementing is outside the loop body. The main difference between the types of loop, however, is that a do/while loop executes at least once, whereas a for (or a while) may not execute.
â€“Â Andy Turner
3 hours ago

It doesn't matter. BTW, with Java 8+, you can also do IntStream.rangeClosed(1, 6).forEach(times -> System.out.println("I have printed " + times + " times."));
â€“Â David Conrad
3 hours ago

To an extent, it comes down to taste. I would prefer to use a for loop in this situtation, because the declaration is scoped to the loop, and incrementing is outside the loop body. The main difference between the types of loop, however, is that a do/while loop executes at least once, whereas a for (or a while) may not execute.
â€“Â Andy Turner
3 hours ago

It doesn't matter. BTW, with Java 8+, you can also do IntStream.rangeClosed(1, 6).forEach(times -> System.out.println("I have printed " + times + " times."));
â€“Â David Conrad
3 hours ago

add a commentÂ |Â

5 Answers
5

active

oldest

votes

up vote
5
down vote

You're right, these do exactly the same thing. If you know in advance (before the loop starts) how many times you want it to iterate, most Java developers will tell you to go with a for loop. That's what it's designed for.

A while loop or do while loop is better suited for situations where you're looking for a specific value or condition before you exit the loop.

answered 3 hours ago

Bill the Lizard

284k156490786

True, I forgot about the fact that, (from personal experiences), nothing executes after the do-while loop, and would just have to keep nesting loops.
â€“Â Domani Tomlindo
3 hours ago

add a commentÂ |Â

up vote
2
down vote

When faced with these kind of dilemmas, aim for readability and familiarity. You should not concern yourself with micro-optimizations. Focus on readability and clearly conveying you intent. Do as other do in similar situation.

Like @Bill-The-Lizard said, while loop suggests to the reader of your code that you opted for it, because you're not counting, but repeating until a condition is met. At least once - otherwise you'd have chosen while(...) loop.

In other words, for, do while() and while() generally work the same. But one may better convey you intent in your particular piece of logic.

answered 3 hours ago

rzymek

6,55223043

add a commentÂ |Â

up vote
0
down vote

I think it's more of a readability and syntactic sugar. This while condition

while (condition)

can also be written as

for (; condition; )

but obviously the first one looks lot better and is more readable.

answered 3 hours ago

stackFan

580618

OP is asking about a do/while loop, not a while loop.
â€“Â Andy Turner
3 hours ago

add a commentÂ |Â

up vote
0
down vote

It depends on the programmer's choice when to use for loop or do while loop but the general practice followed by most of the programmers is

For loop

When you know that the loop will execute a predefined number of times(general practice since you can also use for(;true;) which loops forever).
For example a loop which runs 10 times or n number of times where n is a variable

for(int i = 0; i < n; i++) 
 //Do something

While loop

When you know that the loop should terminate after the evaluation of a specific condition as true or else you want the loop to run forever (like while(true)) and check the break conditions inside the while loop.

Also the while loop is preferred when you can't figure out the conditions in the first place and start with while(true) but once you write code inside the loop you get good understanding of what's happening and get the idea about which conditions to check thus when to exit the loop.
For example

while(x != 0) 
 //Do something;
 x--;

while(true) 
 // some code to execute on which the condition depends
 if(condition is true) 
 break;

Do while loop

Do while loop is similar to the while loop but with a small difference. That is it allows the first iteration to happen without checking the condition(specified in the while statement, but you can still evaluate the condition inside the block(curly braces)).

edited 3 hours ago

answered 3 hours ago

geektl

214

New contributor

add a commentÂ |Â

up vote
0
down vote

By convention most Java developers use for loops. Effective Java recommends for loops instead of while loops because the loop variable can use a tighter scope which reduces bugs. http://www.corejavaguru.com/effective-java/items/45

answered 3 hours ago

neildo

98767

add a commentÂ |Â

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5 Answers
5

active

oldest

votes

5 Answers
5

active

oldest

votes

up vote
5
down vote

A while loop or do while loop is better suited for situations where you're looking for a specific value or condition before you exit the loop.

answered 3 hours ago

Bill the Lizard

284k156490786

True, I forgot about the fact that, (from personal experiences), nothing executes after the do-while loop, and would just have to keep nesting loops.
â€“Â Domani Tomlindo
3 hours ago

add a commentÂ |Â

up vote
5
down vote

A while loop or do while loop is better suited for situations where you're looking for a specific value or condition before you exit the loop.

answered 3 hours ago

Bill the Lizard

284k156490786

True, I forgot about the fact that, (from personal experiences), nothing executes after the do-while loop, and would just have to keep nesting loops.
â€“Â Domani Tomlindo
3 hours ago

add a commentÂ |Â

up vote
5
down vote

A while loop or do while loop is better suited for situations where you're looking for a specific value or condition before you exit the loop.

answered 3 hours ago

Bill the Lizard

284k156490786

A while loop or do while loop is better suited for situations where you're looking for a specific value or condition before you exit the loop.

answered 3 hours ago

Bill the Lizard

284k156490786

answered 3 hours ago

Bill the Lizard

284k156490786

answered 3 hours ago

Bill the Lizard

284k156490786

answered 3 hours ago

Bill the Lizard

284k156490786

True, I forgot about the fact that, (from personal experiences), nothing executes after the do-while loop, and would just have to keep nesting loops.
â€“Â Domani Tomlindo
3 hours ago

add a commentÂ |Â

True, I forgot about the fact that, (from personal experiences), nothing executes after the do-while loop, and would just have to keep nesting loops.
â€“Â Domani Tomlindo
3 hours ago

True, I forgot about the fact that, (from personal experiences), nothing executes after the do-while loop, and would just have to keep nesting loops.
â€“Â Domani Tomlindo
3 hours ago

add a commentÂ |Â

up vote
2
down vote

In other words, for, do while() and while() generally work the same. But one may better convey you intent in your particular piece of logic.

answered 3 hours ago

rzymek

6,55223043

add a commentÂ |Â

up vote
2
down vote

In other words, for, do while() and while() generally work the same. But one may better convey you intent in your particular piece of logic.

answered 3 hours ago

rzymek

6,55223043

add a commentÂ |Â

up vote
2
down vote

In other words, for, do while() and while() generally work the same. But one may better convey you intent in your particular piece of logic.

answered 3 hours ago

rzymek

6,55223043

In other words, for, do while() and while() generally work the same. But one may better convey you intent in your particular piece of logic.

answered 3 hours ago

rzymek

6,55223043

answered 3 hours ago

rzymek

6,55223043

answered 3 hours ago

rzymek

6,55223043

answered 3 hours ago

rzymek

6,55223043

add a commentÂ |Â

up vote
0
down vote

I think it's more of a readability and syntactic sugar. This while condition

while (condition)

can also be written as

for (; condition; )

but obviously the first one looks lot better and is more readable.

answered 3 hours ago

stackFan

580618

OP is asking about a do/while loop, not a while loop.
â€“Â Andy Turner
3 hours ago

add a commentÂ |Â

up vote
0
down vote

I think it's more of a readability and syntactic sugar. This while condition

while (condition)

can also be written as

for (; condition; )

but obviously the first one looks lot better and is more readable.

answered 3 hours ago

stackFan

580618

OP is asking about a do/while loop, not a while loop.
â€“Â Andy Turner
3 hours ago

add a commentÂ |Â

up vote
0
down vote

I think it's more of a readability and syntactic sugar. This while condition

while (condition)

can also be written as

for (; condition; )

but obviously the first one looks lot better and is more readable.

answered 3 hours ago

stackFan

580618

I think it's more of a readability and syntactic sugar. This while condition

while (condition)

can also be written as

for (; condition; )

but obviously the first one looks lot better and is more readable.

answered 3 hours ago

stackFan

580618

answered 3 hours ago

stackFan

580618

answered 3 hours ago

stackFan

580618

answered 3 hours ago

stackFan

580618

OP is asking about a do/while loop, not a while loop.
â€“Â Andy Turner
3 hours ago

add a commentÂ |Â

OP is asking about a do/while loop, not a while loop.
â€“Â Andy Turner
3 hours ago

OP is asking about a do/while loop, not a while loop.
â€“Â Andy Turner
3 hours ago

add a commentÂ |Â

up vote
0
down vote

It depends on the programmer's choice when to use for loop or do while loop but the general practice followed by most of the programmers is

For loop

When you know that the loop will execute a predefined number of times(general practice since you can also use for(;true;) which loops forever).
For example a loop which runs 10 times or n number of times where n is a variable

for(int i = 0; i < n; i++) 
 //Do something

While loop

When you know that the loop should terminate after the evaluation of a specific condition as true or else you want the loop to run forever (like while(true)) and check the break conditions inside the while loop.

Also the while loop is preferred when you can't figure out the conditions in the first place and start with while(true) but once you write code inside the loop you get good understanding of what's happening and get the idea about which conditions to check thus when to exit the loop.
For example

while(x != 0) 
 //Do something;
 x--;

while(true) 
 // some code to execute on which the condition depends
 if(condition is true) 
 break;

Do while loop

Do while loop is similar to the while loop but with a small difference. That is it allows the first iteration to happen without checking the condition(specified in the while statement, but you can still evaluate the condition inside the block(curly braces)).

edited 3 hours ago

answered 3 hours ago

geektl

214

New contributor

add a commentÂ |Â

up vote
0
down vote

It depends on the programmer's choice when to use for loop or do while loop but the general practice followed by most of the programmers is

For loop

When you know that the loop will execute a predefined number of times(general practice since you can also use for(;true;) which loops forever).
For example a loop which runs 10 times or n number of times where n is a variable

for(int i = 0; i < n; i++) 
 //Do something

While loop

When you know that the loop should terminate after the evaluation of a specific condition as true or else you want the loop to run forever (like while(true)) and check the break conditions inside the while loop.

Also the while loop is preferred when you can't figure out the conditions in the first place and start with while(true) but once you write code inside the loop you get good understanding of what's happening and get the idea about which conditions to check thus when to exit the loop.
For example

while(x != 0) 
 //Do something;
 x--;

while(true) 
 // some code to execute on which the condition depends
 if(condition is true) 
 break;

Do while loop

Do while loop is similar to the while loop but with a small difference. That is it allows the first iteration to happen without checking the condition(specified in the while statement, but you can still evaluate the condition inside the block(curly braces)).

edited 3 hours ago

answered 3 hours ago

geektl

214

New contributor

add a commentÂ |Â

up vote
0
down vote

It depends on the programmer's choice when to use for loop or do while loop but the general practice followed by most of the programmers is

For loop

When you know that the loop will execute a predefined number of times(general practice since you can also use for(;true;) which loops forever).
For example a loop which runs 10 times or n number of times where n is a variable

for(int i = 0; i < n; i++) 
 //Do something

While loop

When you know that the loop should terminate after the evaluation of a specific condition as true or else you want the loop to run forever (like while(true)) and check the break conditions inside the while loop.

Also the while loop is preferred when you can't figure out the conditions in the first place and start with while(true) but once you write code inside the loop you get good understanding of what's happening and get the idea about which conditions to check thus when to exit the loop.
For example

while(x != 0) 
 //Do something;
 x--;

while(true) 
 // some code to execute on which the condition depends
 if(condition is true) 
 break;

Do while loop

Do while loop is similar to the while loop but with a small difference. That is it allows the first iteration to happen without checking the condition(specified in the while statement, but you can still evaluate the condition inside the block(curly braces)).

edited 3 hours ago

answered 3 hours ago

geektl

214

New contributor

It depends on the programmer's choice when to use for loop or do while loop but the general practice followed by most of the programmers is

For loop

When you know that the loop will execute a predefined number of times(general practice since you can also use for(;true;) which loops forever).
For example a loop which runs 10 times or n number of times where n is a variable

for(int i = 0; i < n; i++) 
 //Do something

While loop

When you know that the loop should terminate after the evaluation of a specific condition as true or else you want the loop to run forever (like while(true)) and check the break conditions inside the while loop.

Also the while loop is preferred when you can't figure out the conditions in the first place and start with while(true) but once you write code inside the loop you get good understanding of what's happening and get the idea about which conditions to check thus when to exit the loop.
For example

while(x != 0) 
 //Do something;
 x--;

while(true) 
 // some code to execute on which the condition depends
 if(condition is true) 
 break;

Do while loop

Do while loop is similar to the while loop but with a small difference. That is it allows the first iteration to happen without checking the condition(specified in the while statement, but you can still evaluate the condition inside the block(curly braces)).

edited 3 hours ago

answered 3 hours ago

geektl

214

New contributor

edited 3 hours ago

answered 3 hours ago

geektl

214

New contributor

answered 3 hours ago

geektl

214

answered 3 hours ago

geektl

214

New contributor

geektl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

add a commentÂ |Â

up vote
0
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answered 3 hours ago

neildo

98767

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0
down vote

answered 3 hours ago

neildo

98767

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up vote
0
down vote

answered 3 hours ago

neildo

98767

answered 3 hours ago

neildo

98767

answered 3 hours ago

neildo

98767

answered 3 hours ago

neildo

98767

answered 3 hours ago

neildo

98767

add a commentÂ |Â

Domani Tomlindo is a new contributor. Be nice, and check out our Code of Conduct.

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