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Difference between DTO, VO, POJO, JavaBeans?
...eans are reusable software components for Java that can be manipulated visually in a builder tool. Practically, they are classes written in the Java programming language conforming to a particular convention. They are used to encapsulate many objects into a single object (the bean), so that they can...
Configuring Log4j Loggers Programmatically
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You can add/remove Appender programmatically to Log4j:
ConsoleAppender console = new ConsoleAppender(); //create appender
//configure the appender
String PATTERN = "%d [%p|%c|%C{1}] %m%n";
console.setLayout(new PatternLayout(PATTERN));
console.setThresh...
Postgresql - change the size of a varchar column to lower length
I have a question about the ALTER TABLE command on a really large table (almost 30 millions rows).
One of its columns is a varchar(255) and I would like to resize it to a varchar(40) .
Basically, I would like to change my column by running the following command:
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Should I instantiate instance variables on declaration or in the constructor?
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There is no difference - the instance variable initialization is actually put in the constructor(s) by the compiler.
The first variant is more readable.
You can't have exception handling with the first variant.
There is additionally the initialization block, which is as well put in the constru...
Replace spaces with dashes and make all letters lower-case
...games"
Notice the g flag on the RegExp, it will make the replacement globally within the string, if it's not used, only the first occurrence will be replaced, and also, that RegExp will match one or more white-space characters.
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On duplicate key ignore? [duplicate]
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Would suggest NOT using INSERT IGNORE as it ignores ALL errors (ie its a sloppy global ignore).
Instead, since in your example tag is the unique key, use:
INSERT INTO table_tags (tag) VALUES ('tag_a'),('tab_b'),('tag_c') ON DUPLICATE KEY UPDATE tag=tag;
on duplicate key pro...
How to empty (clear) the logcat buffer in Android [duplicate]
...rooted buffers (main, system ..etc).
adb logcat -c
If you want to clear all the buffers (like radio, kernel..etc), Please use the following commands
adb root
adb logcat -b all -c
or
adb root
adb shell logcat -b all -c
Use the following commands to know the list of buffers that device supp...