Convert java.util.Date to String in yyyy-MM-dd format without creating a lot of objects

Clash Royale CLAN TAG#URR8PPP

up vote
8
down vote

favorite

I need to convert java.util.Date to String in yyyy-MM-dd format in a big amounts.

I have just moved to java 8 and want to know how to do it properly.
When using java 7 I was using

DateTimeFormatter DATE_FORMATTER = DateTimeFormat.forPattern(DATE_FORMAT_PATTERN)

and then

DATE_FORMATTER.print(value.getTime())

it helped me not to create a lots of redundant objects

So now when I moved to java 8 I want rewrite it properly but

LocalDate.fromDateFields(value).toString())

creates each time new LocalDate object and this gives a lot of work to GC

Are there any ways to solve my problem?
Performance and thread-safety are very important

java java-8 java-time

share|improve this question

edited 38 mins ago

asked 1 hour ago

Oleksandr Riznyk

21018

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Do you have Date or LocalDate objects?
  – Flown
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Hi, java.util.Date
  – Oleksandr Riznyk
  55 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  There is no need converting to LocalDate, just use the SimpleDateFormat.
  – Flown
  53 mins ago
  

  
  
  
  

add a comment | 

up vote
8
down vote

favorite

I need to convert java.util.Date to String in yyyy-MM-dd format in a big amounts.

I have just moved to java 8 and want to know how to do it properly.
When using java 7 I was using

DateTimeFormatter DATE_FORMATTER = DateTimeFormat.forPattern(DATE_FORMAT_PATTERN)

and then

DATE_FORMATTER.print(value.getTime())

it helped me not to create a lots of redundant objects

So now when I moved to java 8 I want rewrite it properly but

LocalDate.fromDateFields(value).toString())

creates each time new LocalDate object and this gives a lot of work to GC

Are there any ways to solve my problem?
Performance and thread-safety are very important

java java-8 java-time

share|improve this question

edited 38 mins ago

asked 1 hour ago

Oleksandr Riznyk

21018

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Do you have Date or LocalDate objects?
  – Flown
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Hi, java.util.Date
  – Oleksandr Riznyk
  55 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  There is no need converting to LocalDate, just use the SimpleDateFormat.
  – Flown
  53 mins ago
  

  
  
  
  

add a comment | 

up vote
8
down vote

favorite

up vote
8
down vote

favorite

I need to convert java.util.Date to String in yyyy-MM-dd format in a big amounts.

I have just moved to java 8 and want to know how to do it properly.
When using java 7 I was using

DateTimeFormatter DATE_FORMATTER = DateTimeFormat.forPattern(DATE_FORMAT_PATTERN)

and then

DATE_FORMATTER.print(value.getTime())

it helped me not to create a lots of redundant objects

So now when I moved to java 8 I want rewrite it properly but

LocalDate.fromDateFields(value).toString())

creates each time new LocalDate object and this gives a lot of work to GC

Are there any ways to solve my problem?
Performance and thread-safety are very important

java java-8 java-time

share|improve this question

edited 38 mins ago

asked 1 hour ago

Oleksandr Riznyk

21018

I need to convert java.util.Date to String in yyyy-MM-dd format in a big amounts.

I have just moved to java 8 and want to know how to do it properly.
When using java 7 I was using

DateTimeFormatter DATE_FORMATTER = DateTimeFormat.forPattern(DATE_FORMAT_PATTERN)

and then

DATE_FORMATTER.print(value.getTime())

it helped me not to create a lots of redundant objects

So now when I moved to java 8 I want rewrite it properly but

LocalDate.fromDateFields(value).toString())

creates each time new LocalDate object and this gives a lot of work to GC

Are there any ways to solve my problem?
Performance and thread-safety are very important

java java-8 java-time

java java-8 java-time

share|improve this question

edited 38 mins ago

asked 1 hour ago

Oleksandr Riznyk

21018

share|improve this question

edited 38 mins ago

asked 1 hour ago

Oleksandr Riznyk

21018

share|improve this question

share|improve this question

edited 38 mins ago

edited 38 mins ago

edited 38 mins ago

asked 1 hour ago

Oleksandr Riznyk

21018

asked 1 hour ago

Oleksandr Riznyk

21018

asked 1 hour ago

Oleksandr Riznyk

21018

21018

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Do you have Date or LocalDate objects?
  – Flown
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Hi, java.util.Date
  – Oleksandr Riznyk
  55 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  There is no need converting to LocalDate, just use the SimpleDateFormat.
  – Flown
  53 mins ago
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Do you have Date or LocalDate objects?
  – Flown
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Hi, java.util.Date
  – Oleksandr Riznyk
  55 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  There is no need converting to LocalDate, just use the SimpleDateFormat.
  – Flown
  53 mins ago
  

  
  
  
  

1

1

Do you have Date or LocalDate objects?
– Flown
1 hour ago

Do you have Date or LocalDate objects?
– Flown
1 hour ago

Hi, java.util.Date
– Oleksandr Riznyk
55 mins ago

Hi, java.util.Date
– Oleksandr Riznyk
55 mins ago

There is no need converting to LocalDate, just use the SimpleDateFormat.
– Flown
53 mins ago

There is no need converting to LocalDate, just use the SimpleDateFormat.
– Flown
53 mins ago

add a comment | 

6 Answers
6

active

oldest

votes

up vote
3
down vote

The following only has an overhead for the conversion of the old Date to the new LocalDate.

 Date date = new Date();
 LocalDate ldate = LocalDate.from(date.toInstant());
 String s = DateTimeFormatter.ISO_DATE.format(ldate); // uuuu-MM-dd

It is true however that DateTimeFormatters are thread-safe and hence will have one instantiation more per call.

share|improve this answer

answered 51 mins ago

Joop Eggen

74.4k754100

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Good idea I didn't notice that I can use date.toInstant() already with the static method LocalDate.from(), this reduces the part of specifing a time zone. +1
  – 0x1C1B
  41 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  This snippet throws an exception on 1.8.0_181 and 11
  – Flown
  36 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @Flown You're right also on JDK10 what's the problem?
  – 0x1C1B
  33 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Should be LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC))
  – Flown
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @Flown Is LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC)) faster than date.toInstant().atZone(ZoneOffset.UTC).toLocalDate();?
  – 0x1C1B
  23 mins ago
  

  
  
  
  

 | 
show 2 more comments

up vote
1
down vote

I don't have exact numbers from point of view of the performance but I would use the Java 8 Time API to solve this issue. In your special case I would use the following statement:

LocalDate.now().format(DateTimeFormatter.ISO_DATE);

EDIT:
For this solution is a conversion from java.util.Date to java.time.LocalDate required!

new Date().toInstant().atZone(ZoneId.systemDefault()).toLocalDate();

share|improve this answer

edited 48 mins ago

answered 53 mins ago

0x1C1B

47012

add a comment | 

up vote
1
down vote

Use SimpleDateFormat to format Date.

watch out, SDF is NOT THREAD-SAFE, it might not be important but keep that in mind.

For Example:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println((sdf.format(new Date())).toString());

LINK with more information.

share|improve this answer

edited 42 mins ago

answered 52 mins ago

Emil Hotkowski

758312

• 
  
  
  

  
  

  
  
  
  
  
  

  
  The method parse(String) in the type DateFormat is not applicable for the arguments (Date)
  – Selaron
  47 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  yeah, i meant format :) nice catch
  – Emil Hotkowski
  41 mins ago
  

  
  
  
  

add a comment | 

up vote
0
down vote

I would suggest you try out Joda Time for DateTime-related operations.
Joda Time Maven

share|improve this answer

answered 1 hour ago

Nagaraja R

43

• 
  
  
  

  
  

  
  
  
  
  
  

  
  thanks but my solution from Java 7 is already uses Joda Time. I would like do know if Java 8 provides any better solutions?
  – Oleksandr Riznyk
  1 hour ago
  
  

  
  
  
  

add a comment | 

up vote
0
down vote

Without creating lots of objects, meaning you want the performance version?

public static String getIsoDate(java.util.Date time) 
 java.util.Calendar cal = java.util.Calendar.getInstance();
 cal.setTime(time);
 StringBuilder sb = new StringBuilder();
 int year = cal.get(java.util.Calendar.YEAR);
 int month = cal.get(java.util.Calendar.MONTH);
 int day = cal.get(java.util.Calendar.DAY_OF_MONTH);
 sb.append(year);
 sb.append('-');
 if (month < 10) 
 sb.append('0');
 
 sb.append(month);
 sb.append('-');
 if (day < 10) 
 sb.append('0');
 
 sb.append(day);
 return sb.toString();

This version is thread-safe and avoids most hidden object creations, and unless you have years under 1000 or over 9999, it will print just fine.

share|improve this answer

answered 32 mins ago

coladict

1,601517

• 
  
  
  

  
  

  
  
  
  
  
  

  
  This isn't offensive it's actually interest, are you sure that this code is faster than converting it to LocalDate and using the Java 8 Time API? I mean, I'm definetly not a performance freak, but it seems that this is a lot of code with memory allocation... Seems to be interesting...
  – 0x1C1B
  25 mins ago
  

  
  
  
  

add a comment | 

up vote
-1
down vote

Use SimpleDateFormat to format Date in your expected format.

For Example:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println((sdf.parse("2019-08-31")).toString());

share|improve this answer

answered 58 mins ago

Busy Bee

7251618

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Hi, i need to convert java.util.Date object to String, but your code is used for parsing Date from String which I do not have at this moment
  – Oleksandr Riznyk
  55 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  how do you want to do it then?
  – Busy Bee
  49 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  I don't understand your question but in your solution you parsing a date from string but my target is to parse string it is the question
  – Oleksandr Riznyk
  44 mins ago
  

  
  
  
  

add a comment | 

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6 Answers
6

active

oldest

votes

6 Answers
6

active

oldest

votes

active

oldest

votes

active

oldest

votes

up vote
3
down vote

The following only has an overhead for the conversion of the old Date to the new LocalDate.

 Date date = new Date();
 LocalDate ldate = LocalDate.from(date.toInstant());
 String s = DateTimeFormatter.ISO_DATE.format(ldate); // uuuu-MM-dd

It is true however that DateTimeFormatters are thread-safe and hence will have one instantiation more per call.

share|improve this answer

answered 51 mins ago

Joop Eggen

74.4k754100

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Good idea I didn't notice that I can use date.toInstant() already with the static method LocalDate.from(), this reduces the part of specifing a time zone. +1
  – 0x1C1B
  41 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  This snippet throws an exception on 1.8.0_181 and 11
  – Flown
  36 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @Flown You're right also on JDK10 what's the problem?
  – 0x1C1B
  33 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Should be LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC))
  – Flown
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @Flown Is LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC)) faster than date.toInstant().atZone(ZoneOffset.UTC).toLocalDate();?
  – 0x1C1B
  23 mins ago
  

  
  
  
  

 | 
show 2 more comments

up vote
3
down vote

The following only has an overhead for the conversion of the old Date to the new LocalDate.

 Date date = new Date();
 LocalDate ldate = LocalDate.from(date.toInstant());
 String s = DateTimeFormatter.ISO_DATE.format(ldate); // uuuu-MM-dd

It is true however that DateTimeFormatters are thread-safe and hence will have one instantiation more per call.

share|improve this answer

answered 51 mins ago

Joop Eggen

74.4k754100

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Good idea I didn't notice that I can use date.toInstant() already with the static method LocalDate.from(), this reduces the part of specifing a time zone. +1
  – 0x1C1B
  41 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  This snippet throws an exception on 1.8.0_181 and 11
  – Flown
  36 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @Flown You're right also on JDK10 what's the problem?
  – 0x1C1B
  33 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Should be LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC))
  – Flown
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @Flown Is LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC)) faster than date.toInstant().atZone(ZoneOffset.UTC).toLocalDate();?
  – 0x1C1B
  23 mins ago
  

  
  
  
  

 | 
show 2 more comments

up vote
3
down vote

up vote
3
down vote

The following only has an overhead for the conversion of the old Date to the new LocalDate.

 Date date = new Date();
 LocalDate ldate = LocalDate.from(date.toInstant());
 String s = DateTimeFormatter.ISO_DATE.format(ldate); // uuuu-MM-dd

It is true however that DateTimeFormatters are thread-safe and hence will have one instantiation more per call.

share|improve this answer

answered 51 mins ago

Joop Eggen

74.4k754100

The following only has an overhead for the conversion of the old Date to the new LocalDate.

 Date date = new Date();
 LocalDate ldate = LocalDate.from(date.toInstant());
 String s = DateTimeFormatter.ISO_DATE.format(ldate); // uuuu-MM-dd

It is true however that DateTimeFormatters are thread-safe and hence will have one instantiation more per call.

share|improve this answer

answered 51 mins ago

Joop Eggen

74.4k754100

share|improve this answer

share|improve this answer

answered 51 mins ago

Joop Eggen

74.4k754100

answered 51 mins ago

Joop Eggen

74.4k754100

answered 51 mins ago

Joop Eggen

74.4k754100

74.4k754100

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Good idea I didn't notice that I can use date.toInstant() already with the static method LocalDate.from(), this reduces the part of specifing a time zone. +1
  – 0x1C1B
  41 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  This snippet throws an exception on 1.8.0_181 and 11
  – Flown
  36 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @Flown You're right also on JDK10 what's the problem?
  – 0x1C1B
  33 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Should be LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC))
  – Flown
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @Flown Is LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC)) faster than date.toInstant().atZone(ZoneOffset.UTC).toLocalDate();?
  – 0x1C1B
  23 mins ago
  

  
  
  
  

 | 
show 2 more comments

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Good idea I didn't notice that I can use date.toInstant() already with the static method LocalDate.from(), this reduces the part of specifing a time zone. +1
  – 0x1C1B
  41 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  This snippet throws an exception on 1.8.0_181 and 11
  – Flown
  36 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @Flown You're right also on JDK10 what's the problem?
  – 0x1C1B
  33 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Should be LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC))
  – Flown
  31 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  @Flown Is LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC)) faster than date.toInstant().atZone(ZoneOffset.UTC).toLocalDate();?
  – 0x1C1B
  23 mins ago
  

  
  
  
  

Good idea I didn't notice that I can use date.toInstant() already with the static method LocalDate.from(), this reduces the part of specifing a time zone. +1
– 0x1C1B
41 mins ago

Good idea I didn't notice that I can use date.toInstant() already with the static method LocalDate.from(), this reduces the part of specifing a time zone. +1
– 0x1C1B
41 mins ago

1

1

This snippet throws an exception on 1.8.0_181 and 11
– Flown
36 mins ago

This snippet throws an exception on 1.8.0_181 and 11
– Flown
36 mins ago

@Flown You're right also on JDK10 what's the problem?
– 0x1C1B
33 mins ago

@Flown You're right also on JDK10 what's the problem?
– 0x1C1B
33 mins ago

1

1

Should be LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC))
– Flown
31 mins ago

Should be LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC))
– Flown
31 mins ago

@Flown Is LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC)) faster than date.toInstant().atZone(ZoneOffset.UTC).toLocalDate();?
– 0x1C1B
23 mins ago

@Flown Is LocalDate.from(date.toInstant().atZone(ZoneOffset.UTC)) faster than date.toInstant().atZone(ZoneOffset.UTC).toLocalDate();?
– 0x1C1B
23 mins ago

 | 
show 2 more comments

up vote
1
down vote

I don't have exact numbers from point of view of the performance but I would use the Java 8 Time API to solve this issue. In your special case I would use the following statement:

LocalDate.now().format(DateTimeFormatter.ISO_DATE);

EDIT:
For this solution is a conversion from java.util.Date to java.time.LocalDate required!

new Date().toInstant().atZone(ZoneId.systemDefault()).toLocalDate();

share|improve this answer

edited 48 mins ago

answered 53 mins ago

0x1C1B

47012

add a comment | 

up vote
1
down vote

I don't have exact numbers from point of view of the performance but I would use the Java 8 Time API to solve this issue. In your special case I would use the following statement:

LocalDate.now().format(DateTimeFormatter.ISO_DATE);

EDIT:
For this solution is a conversion from java.util.Date to java.time.LocalDate required!

new Date().toInstant().atZone(ZoneId.systemDefault()).toLocalDate();

share|improve this answer

edited 48 mins ago

answered 53 mins ago

0x1C1B

47012

add a comment | 

up vote
1
down vote

up vote
1
down vote

I don't have exact numbers from point of view of the performance but I would use the Java 8 Time API to solve this issue. In your special case I would use the following statement:

LocalDate.now().format(DateTimeFormatter.ISO_DATE);

EDIT:
For this solution is a conversion from java.util.Date to java.time.LocalDate required!

new Date().toInstant().atZone(ZoneId.systemDefault()).toLocalDate();

share|improve this answer

edited 48 mins ago

answered 53 mins ago

0x1C1B

47012

I don't have exact numbers from point of view of the performance but I would use the Java 8 Time API to solve this issue. In your special case I would use the following statement:

LocalDate.now().format(DateTimeFormatter.ISO_DATE);

EDIT:
For this solution is a conversion from java.util.Date to java.time.LocalDate required!

new Date().toInstant().atZone(ZoneId.systemDefault()).toLocalDate();

share|improve this answer

edited 48 mins ago

answered 53 mins ago

0x1C1B

47012

share|improve this answer

share|improve this answer

edited 48 mins ago

edited 48 mins ago

edited 48 mins ago

answered 53 mins ago

0x1C1B

47012

answered 53 mins ago

0x1C1B

47012

answered 53 mins ago

0x1C1B

47012

47012

add a comment | 

add a comment | 

up vote
1
down vote

Use SimpleDateFormat to format Date.

watch out, SDF is NOT THREAD-SAFE, it might not be important but keep that in mind.

For Example:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println((sdf.format(new Date())).toString());

LINK with more information.

share|improve this answer

edited 42 mins ago

answered 52 mins ago

Emil Hotkowski

758312

• 
  
  
  

  
  

  
  
  
  
  
  

  
  The method parse(String) in the type DateFormat is not applicable for the arguments (Date)
  – Selaron
  47 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  yeah, i meant format :) nice catch
  – Emil Hotkowski
  41 mins ago
  

  
  
  
  

add a comment | 

up vote
1
down vote

Use SimpleDateFormat to format Date.

watch out, SDF is NOT THREAD-SAFE, it might not be important but keep that in mind.

For Example:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println((sdf.format(new Date())).toString());

LINK with more information.

share|improve this answer

edited 42 mins ago

answered 52 mins ago

Emil Hotkowski

758312

• 
  
  
  

  
  

  
  
  
  
  
  

  
  The method parse(String) in the type DateFormat is not applicable for the arguments (Date)
  – Selaron
  47 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  yeah, i meant format :) nice catch
  – Emil Hotkowski
  41 mins ago
  

  
  
  
  

add a comment | 

up vote
1
down vote

up vote
1
down vote

Use SimpleDateFormat to format Date.

watch out, SDF is NOT THREAD-SAFE, it might not be important but keep that in mind.

For Example:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println((sdf.format(new Date())).toString());

LINK with more information.

share|improve this answer

edited 42 mins ago

answered 52 mins ago

Emil Hotkowski

758312

Use SimpleDateFormat to format Date.

watch out, SDF is NOT THREAD-SAFE, it might not be important but keep that in mind.

For Example:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println((sdf.format(new Date())).toString());

LINK with more information.

share|improve this answer

edited 42 mins ago

answered 52 mins ago

Emil Hotkowski

758312

share|improve this answer

share|improve this answer

edited 42 mins ago

edited 42 mins ago

edited 42 mins ago

answered 52 mins ago

Emil Hotkowski

758312

answered 52 mins ago

Emil Hotkowski

758312

answered 52 mins ago

Emil Hotkowski

758312

758312

• 
  
  
  

  
  

  
  
  
  
  
  

  
  The method parse(String) in the type DateFormat is not applicable for the arguments (Date)
  – Selaron
  47 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  yeah, i meant format :) nice catch
  – Emil Hotkowski
  41 mins ago
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  

  
  
  
  
  
  

  
  The method parse(String) in the type DateFormat is not applicable for the arguments (Date)
  – Selaron
  47 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  yeah, i meant format :) nice catch
  – Emil Hotkowski
  41 mins ago
  

  
  
  
  

The method parse(String) in the type DateFormat is not applicable for the arguments (Date)
– Selaron
47 mins ago

The method parse(String) in the type DateFormat is not applicable for the arguments (Date)
– Selaron
47 mins ago

yeah, i meant format :) nice catch
– Emil Hotkowski
41 mins ago

yeah, i meant format :) nice catch
– Emil Hotkowski
41 mins ago

add a comment | 

up vote
0
down vote

I would suggest you try out Joda Time for DateTime-related operations.
Joda Time Maven

share|improve this answer

answered 1 hour ago

Nagaraja R

43

• 
  
  
  

  
  

  
  
  
  
  
  

  
  thanks but my solution from Java 7 is already uses Joda Time. I would like do know if Java 8 provides any better solutions?
  – Oleksandr Riznyk
  1 hour ago
  
  

  
  
  
  

add a comment | 

up vote
0
down vote

I would suggest you try out Joda Time for DateTime-related operations.
Joda Time Maven

share|improve this answer

answered 1 hour ago

Nagaraja R

43

• 
  
  
  

  
  

  
  
  
  
  
  

  
  thanks but my solution from Java 7 is already uses Joda Time. I would like do know if Java 8 provides any better solutions?
  – Oleksandr Riznyk
  1 hour ago
  
  

  
  
  
  

add a comment | 

up vote
0
down vote

up vote
0
down vote

I would suggest you try out Joda Time for DateTime-related operations.
Joda Time Maven

share|improve this answer

answered 1 hour ago

Nagaraja R

43

I would suggest you try out Joda Time for DateTime-related operations.
Joda Time Maven

share|improve this answer

answered 1 hour ago

Nagaraja R

43

share|improve this answer

share|improve this answer

answered 1 hour ago

Nagaraja R

43

answered 1 hour ago

Nagaraja R

43

answered 1 hour ago

Nagaraja R

43

43

• 
  
  
  

  
  

  
  
  
  
  
  

  
  thanks but my solution from Java 7 is already uses Joda Time. I would like do know if Java 8 provides any better solutions?
  – Oleksandr Riznyk
  1 hour ago
  
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  

  
  
  
  
  
  

  
  thanks but my solution from Java 7 is already uses Joda Time. I would like do know if Java 8 provides any better solutions?
  – Oleksandr Riznyk
  1 hour ago
  
  

  
  
  
  

thanks but my solution from Java 7 is already uses Joda Time. I would like do know if Java 8 provides any better solutions?
– Oleksandr Riznyk
1 hour ago

thanks but my solution from Java 7 is already uses Joda Time. I would like do know if Java 8 provides any better solutions?
– Oleksandr Riznyk
1 hour ago

add a comment | 

up vote
0
down vote

Without creating lots of objects, meaning you want the performance version?

public static String getIsoDate(java.util.Date time) 
 java.util.Calendar cal = java.util.Calendar.getInstance();
 cal.setTime(time);
 StringBuilder sb = new StringBuilder();
 int year = cal.get(java.util.Calendar.YEAR);
 int month = cal.get(java.util.Calendar.MONTH);
 int day = cal.get(java.util.Calendar.DAY_OF_MONTH);
 sb.append(year);
 sb.append('-');
 if (month < 10) 
 sb.append('0');
 
 sb.append(month);
 sb.append('-');
 if (day < 10) 
 sb.append('0');
 
 sb.append(day);
 return sb.toString();

This version is thread-safe and avoids most hidden object creations, and unless you have years under 1000 or over 9999, it will print just fine.

share|improve this answer

answered 32 mins ago

coladict

1,601517

• 
  
  
  

  
  

  
  
  
  
  
  

  
  This isn't offensive it's actually interest, are you sure that this code is faster than converting it to LocalDate and using the Java 8 Time API? I mean, I'm definetly not a performance freak, but it seems that this is a lot of code with memory allocation... Seems to be interesting...
  – 0x1C1B
  25 mins ago
  

  
  
  
  

add a comment | 

up vote
0
down vote

Without creating lots of objects, meaning you want the performance version?

public static String getIsoDate(java.util.Date time) 
 java.util.Calendar cal = java.util.Calendar.getInstance();
 cal.setTime(time);
 StringBuilder sb = new StringBuilder();
 int year = cal.get(java.util.Calendar.YEAR);
 int month = cal.get(java.util.Calendar.MONTH);
 int day = cal.get(java.util.Calendar.DAY_OF_MONTH);
 sb.append(year);
 sb.append('-');
 if (month < 10) 
 sb.append('0');
 
 sb.append(month);
 sb.append('-');
 if (day < 10) 
 sb.append('0');
 
 sb.append(day);
 return sb.toString();

This version is thread-safe and avoids most hidden object creations, and unless you have years under 1000 or over 9999, it will print just fine.

share|improve this answer

answered 32 mins ago

coladict

1,601517

• 
  
  
  

  
  

  
  
  
  
  
  

  
  This isn't offensive it's actually interest, are you sure that this code is faster than converting it to LocalDate and using the Java 8 Time API? I mean, I'm definetly not a performance freak, but it seems that this is a lot of code with memory allocation... Seems to be interesting...
  – 0x1C1B
  25 mins ago
  

  
  
  
  

add a comment | 

up vote
0
down vote

up vote
0
down vote

Without creating lots of objects, meaning you want the performance version?

public static String getIsoDate(java.util.Date time) 
 java.util.Calendar cal = java.util.Calendar.getInstance();
 cal.setTime(time);
 StringBuilder sb = new StringBuilder();
 int year = cal.get(java.util.Calendar.YEAR);
 int month = cal.get(java.util.Calendar.MONTH);
 int day = cal.get(java.util.Calendar.DAY_OF_MONTH);
 sb.append(year);
 sb.append('-');
 if (month < 10) 
 sb.append('0');
 
 sb.append(month);
 sb.append('-');
 if (day < 10) 
 sb.append('0');
 
 sb.append(day);
 return sb.toString();

This version is thread-safe and avoids most hidden object creations, and unless you have years under 1000 or over 9999, it will print just fine.

share|improve this answer

answered 32 mins ago

coladict

1,601517

Without creating lots of objects, meaning you want the performance version?

public static String getIsoDate(java.util.Date time) 
 java.util.Calendar cal = java.util.Calendar.getInstance();
 cal.setTime(time);
 StringBuilder sb = new StringBuilder();
 int year = cal.get(java.util.Calendar.YEAR);
 int month = cal.get(java.util.Calendar.MONTH);
 int day = cal.get(java.util.Calendar.DAY_OF_MONTH);
 sb.append(year);
 sb.append('-');
 if (month < 10) 
 sb.append('0');
 
 sb.append(month);
 sb.append('-');
 if (day < 10) 
 sb.append('0');
 
 sb.append(day);
 return sb.toString();

This version is thread-safe and avoids most hidden object creations, and unless you have years under 1000 or over 9999, it will print just fine.

share|improve this answer

answered 32 mins ago

coladict

1,601517

share|improve this answer

share|improve this answer

answered 32 mins ago

coladict

1,601517

answered 32 mins ago

coladict

1,601517

answered 32 mins ago

coladict

1,601517

1,601517

• 
  
  
  

  
  

  
  
  
  
  
  

  
  This isn't offensive it's actually interest, are you sure that this code is faster than converting it to LocalDate and using the Java 8 Time API? I mean, I'm definetly not a performance freak, but it seems that this is a lot of code with memory allocation... Seems to be interesting...
  – 0x1C1B
  25 mins ago
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  

  
  
  
  
  
  

  
  This isn't offensive it's actually interest, are you sure that this code is faster than converting it to LocalDate and using the Java 8 Time API? I mean, I'm definetly not a performance freak, but it seems that this is a lot of code with memory allocation... Seems to be interesting...
  – 0x1C1B
  25 mins ago
  

  
  
  
  

This isn't offensive it's actually interest, are you sure that this code is faster than converting it to LocalDate and using the Java 8 Time API? I mean, I'm definetly not a performance freak, but it seems that this is a lot of code with memory allocation... Seems to be interesting...
– 0x1C1B
25 mins ago

This isn't offensive it's actually interest, are you sure that this code is faster than converting it to LocalDate and using the Java 8 Time API? I mean, I'm definetly not a performance freak, but it seems that this is a lot of code with memory allocation... Seems to be interesting...
– 0x1C1B
25 mins ago

add a comment | 

up vote
-1
down vote

Use SimpleDateFormat to format Date in your expected format.

For Example:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println((sdf.parse("2019-08-31")).toString());

share|improve this answer

answered 58 mins ago

Busy Bee

7251618

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Hi, i need to convert java.util.Date object to String, but your code is used for parsing Date from String which I do not have at this moment
  – Oleksandr Riznyk
  55 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  how do you want to do it then?
  – Busy Bee
  49 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  I don't understand your question but in your solution you parsing a date from string but my target is to parse string it is the question
  – Oleksandr Riznyk
  44 mins ago
  

  
  
  
  

add a comment | 

up vote
-1
down vote

Use SimpleDateFormat to format Date in your expected format.

For Example:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println((sdf.parse("2019-08-31")).toString());

share|improve this answer

answered 58 mins ago

Busy Bee

7251618

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Hi, i need to convert java.util.Date object to String, but your code is used for parsing Date from String which I do not have at this moment
  – Oleksandr Riznyk
  55 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  how do you want to do it then?
  – Busy Bee
  49 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  I don't understand your question but in your solution you parsing a date from string but my target is to parse string it is the question
  – Oleksandr Riznyk
  44 mins ago
  

  
  
  
  

add a comment | 

up vote
-1
down vote

up vote
-1
down vote

Use SimpleDateFormat to format Date in your expected format.

For Example:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println((sdf.parse("2019-08-31")).toString());

share|improve this answer

answered 58 mins ago

Busy Bee

7251618

Use SimpleDateFormat to format Date in your expected format.

For Example:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println((sdf.parse("2019-08-31")).toString());

share|improve this answer

answered 58 mins ago

Busy Bee

7251618

share|improve this answer

share|improve this answer

answered 58 mins ago

Busy Bee

7251618

answered 58 mins ago

Busy Bee

7251618

answered 58 mins ago

Busy Bee

7251618

7251618

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Hi, i need to convert java.util.Date object to String, but your code is used for parsing Date from String which I do not have at this moment
  – Oleksandr Riznyk
  55 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  how do you want to do it then?
  – Busy Bee
  49 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  I don't understand your question but in your solution you parsing a date from string but my target is to parse string it is the question
  – Oleksandr Riznyk
  44 mins ago
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  

  
  
  
  
  
  

  
  Hi, i need to convert java.util.Date object to String, but your code is used for parsing Date from String which I do not have at this moment
  – Oleksandr Riznyk
  55 mins ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  how do you want to do it then?
  – Busy Bee
  49 mins ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  I don't understand your question but in your solution you parsing a date from string but my target is to parse string it is the question
  – Oleksandr Riznyk
  44 mins ago
  

  
  
  
  

Hi, i need to convert java.util.Date object to String, but your code is used for parsing Date from String which I do not have at this moment
– Oleksandr Riznyk
55 mins ago

Hi, i need to convert java.util.Date object to String, but your code is used for parsing Date from String which I do not have at this moment
– Oleksandr Riznyk
55 mins ago

how do you want to do it then?
– Busy Bee
49 mins ago

how do you want to do it then?
– Busy Bee
49 mins ago

1

1

I don't understand your question but in your solution you parsing a date from string but my target is to parse string it is the question
– Oleksandr Riznyk
44 mins ago

I don't understand your question but in your solution you parsing a date from string but my target is to parse string it is the question
– Oleksandr Riznyk
44 mins ago

add a comment | 

 

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