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How to convert a Map to List in Java?
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Using the Java 8 Streams API.
List<Value> values = map.values().stream().collect(Collectors.toList());
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Is null check needed before calling instanceof?
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The expression x instanceof SomeClass is false if x is null.
From the Java Language Specification, section 15.20.2, "Type comparison operator instanceof":
"At run time, the result of the
instanceof operator is true if the
value of the RelationalExpression is
not null and the referenc...
Sprintf equivalent in Java
Printf got added to Java with the 1.5 release but I can't seem to find how to send the output to a string rather than a file (which is what sprintf does in C). Does anyone know how to do this?
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Does JavaScript have the interface type (such as Java's 'interface')?
I'm learning how to make OOP with JavaScript . Does it have the interface concept (such as Java's interface )?
13 Answer...
What's the (hidden) cost of Scala's lazy val?
...he scala mailing list and gives implementation details of lazy in terms of Java code (rather than bytecode):
class LazyTest {
lazy val msg = "Lazy"
}
is compiled to something equivalent to the following Java code:
class LazyTest {
public int bitmap$0;
private String msg;
public String m...
Mail multipart/alternative vs multipart/mixed
...ine image
inline image
attachment
attachment
And the code is:
import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.URLDataSource;
import javax.mail.BodyPart;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.interne...
Printing HashMap In Java
...();
System.out.println(key + " " + value);
}
Update for Java8:
example.entrySet().forEach(entry->{
System.out.println(entry.getKey() + " " + entry.getValue());
});
If you don't require to print key value and just need the hashmap value, you can use others' suggesti...
OpenJDK availability for Windows OS [closed]
...rsion available to Windows OS? From the OpenJDK home page ( http://openjdk.java.net/ ) it redirects to Oracle Sun JRE for Windows machine.
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Java `final` method: what does it promise?
In a Java class a method can be defined to be final , to mark that this method may not be overridden:
5 Answers
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Why cannot cast Integer to String in java?
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No. Every object can be casted to an java.lang.Object, not a String. If you want a string representation of whatever object, you have to invoke the toString() method; this is not the same as casting the object to a String.
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