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Why is Class.newInstance() “evil”?
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The Java API documentation explains why (http://java.sun.com/javase/6/docs/api/java/lang/Class.html#newInstance()):
Note that this method propagates any exception thrown by the nullary constructor, including a checked excepti...
kill -3 to get java thread dump
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With Java 8 in picture, jcmd is the preferred approach.
jcmd <PID> Thread.print
Following is the snippet from Oracle documentation :
The release of JDK 8 introduced Java Mission Control, Java Flight Recorder, and jcmd ...
Double vs. BigDecimal?
...mal. Otherwise Doubles tend to be good enough.
I do recommend reading the javadoc of BigDecimal as they do explain things better than I do here :)
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How to print out all the elements of a List in Java?
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Since Java 8, List inherits a default "forEach" method which you can combine with the method reference "System.out::println" like this:
list.forEach(System.out::println);
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Get string character by index - Java
...ystem.out.println(charAtZero); // Prints f
For more information, see the Java documentation on String.charAt. If you want another simple tutorial, this one or this one.
If you don't want the result as a char data type, but rather as a string, you would use the Character.toString method:
String t...
How to capitalize the first letter of a String in Java?
I am using Java to get a String input from the user. I am trying to make the first letter of this input capitalized.
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How are Anonymous inner classes used in Java?
What is the use of anonymous classes in Java? Can we say that usage of anonymous class is one of the advantages of Java?
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Difference between timestamps with/without time zone in PostgreSQL
...d '2011-07-01 06:30:30+05' are the same as just '2011-07-01 06:30:30'.
For Java developers: it's analogous to java.time.LocalDateTime.
TIMESTAMP WITH TIME ZONE stores a point on the UTC time line. How it looks (how many hours, minutes, etc.) depends on your time zone, but it always refers to the sam...
各编程语言读写文件汇总 - C/C++ - 清泛网 - 专注C/C++及内核技术
...文本读写
3.2、fread、fwrite二进制读写
四、C++
五、Java
PHP读写文件：
// 写文件
$fp = fopen("log.txt", "a");
fwrite($fp, $str);
fclose($fp);
// 读文件
$fp = fopen("log.txt", "r");
while(!feof($fp)) {
$line = fgets($fp);
echo $line;
}
fclose($fp)...
How to read environment variables in Scala
In Java, reading environment variables is done with System.getenv() .
6 Answers
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