大约有 9,000 项符合查询结果（耗时：0.0278秒） [XML]
Java “user.dir” property - what exactly does it mean?
...
It's the directory where java was run from, where you started the JVM. Does not have to be within the user's home directory. It can be anywhere where the user has permission to run java.
So if you cd into /somedir, then run your program, user.dir w...
Why Java needs Serializable interface?
...f this form makes the class internals part of the public API (which is why javadoc gives you the persisted forms of classes).
For long-term persistence, the class must be able to decode this form, which restricts the changes you can make to class design. This breaks encapsulation.
Serialization ca...
Which Java Collection should I use?
...
@MattBall I agree with you for the most part. However Java LinkedList is a double linked list, so access at start and at end are both fast. You will note that of the branches above all three questions have to answer yes before I'd recommend using the LinkedList - so in other wor...
When should assertions stay in production code? [closed]
There's a discussion going on over at comp.lang.c++.moderated about whether or not assertions, which in C++ only exist in debug builds by default, should be kept in production code or not.
...
JPA or JDBC, how are they different?
I am learning Java EE and I downloaded the eclipse with glassfish for the same. I saw some examples and also read the Oracle docs to know all about Java EE 5. Connecting to a database was very simple. I opened a dynamic web project, created a session EJB , I used EntityManager and with the get meth...
Java int to String - Integer.toString(i) vs new Integer(i).toString()
Sometimes java puzzles me.
I have a huge amount of int initializations to make.
11 Answers
...
Best practices for in-app database migration for Sqlite
...isting tables in-place. See the documentation here: http://www.sqlite.org/lang_altertable.html. For deleting columns or other changes that aren't supported by the "ALTER TABLE" syntax, I create a new table, migrate date into it, drop the old table, and rename the new table to the original name.
...
Java: Get first item from a collection
...
In java 8:
Optional<String> firstElement = collection.stream().findFirst();
For older versions of java, there is a getFirst method in Guava Iterables:
Iterables.getFirst(iterable, defaultValue)
...
IntelliJ not recognizing a particular file correctly, instead its stuck as a text file
... note for googlers happening upon this, I had the exact same issue (with a Java file) with the same resolution; IntelliJ 13. When trying to create the file, I encountered the error 'Unable to parse template "Interface" Selected class file name mapped to not java'. Couldn't find that error message an...
How to sort an ArrayList?
I have a List of doubles in java and I want to sort ArrayList in descending order.
20 Answers
...