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How to quit a java app from within the program
What's the best way to quit a Java application with code?
12 Answers
12
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How to force garbage collection in Java?
Is it possible to force garbage collection in Java, even if it is tricky to do? I know about System.gc(); and Runtime.gc(); but they only suggest to do GC. How can I force GC?
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Is it possible to read the value of a annotation in java?
...opied the link here so people can use it.
Example from this page:
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.reflect.Method;
@Retention(RetentionPolicy.RUNTIME)
@interface MyAnno {
String str();
int val();
}
class Meta {
@MyAnno(s...
Converting java.util.Properties to HashMap
java.util.Properties is a implementation of java.util.Map , And java.util.HashMap's constructor receives a Map type param. So, why must it be converted explicitly?
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How to convert hashmap to JSON object in Java
How to convert or cast hashmap to JSON object in Java, and again convert JSON object to JSON string?
29 Answers
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package R does not exist
...anifest.xml file.
If there are no errors in the resource XML files, the R.java source
will be generated in a package subdirectory below gen/ and compiled.
There is another R class located in the android package. This android.R class contains some nested classes, which in turn contain ids and oth...
instanceof Vs getClass( )
...instanceof String using reflection is String.getClass().isInstance(o). The javadoc even says so: This method is the dynamic equivalent of the Java language instanceof operator.
– Andreas
Jun 10 '18 at 21:04
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Concatenating null strings in Java [duplicate]
...m.out.println(s); // prints "nullhello"
(You can do so yourself by using javap -c)
The append methods of StringBuilder all handle null just fine. In this case because null is the first argument, String.valueOf() is invoked instead since StringBuilder does not have a constructor that takes any ar...
How do you input commandline argument in IntelliJ IDEA?
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What if I wanna use a redirect symbol? For example, $ javac Filter WhiteList.txt < TotalList.txt, how can I run this in Intellij just like command lines?
– Wulfric Lee
Sep 9 '16 at 1:26
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How to quickly and conveniently create a one element arraylist [duplicate]
...List like
return new ArrayList<String>(Arrays.asList(s));
and (in Java 7+) you can use the diamond operator <> to make it
return new ArrayList<>(Arrays.asList(s));
Single Element List
Collections can return a list with a single element with list being immutable:
Collection...