Eclipse is defaulting to Java 1.5 and you have classes implementing interface methods (which in Java 1.6 can be annotated with @Override, but in Java 1.5 can only be applied to methods overriding a superclass method). Go to your project/IDE preferences and set the Java compiler level to 1.6 and also make sure you select … Read more
A wait can be “woken up” by another thread calling notify on the monitor which is being waited on whereas a sleep cannot. Also a wait (and notify) must happen in a block synchronized on the monitor object whereas sleep does not: Object mon = …; synchronized (mon) { mon.wait(); } At this point the … Read more
The flag Xmx specifies the maximum memory allocation pool for a Java Virtual Machine (JVM), while Xms specifies the initial memory allocation pool. This means that your JVM will be started with Xms amount of memory and will be able to use a maximum of Xmx amount of memory. For example, starting a JVM like … Read more
Unicode decoding takes place before any other lexical translation. The key benefit of this is that it makes it trivial to go back and forth between ASCII and any other encoding. You don’t even need to figure out where comments begin and end! As stated in JLS Section 3.3 this allows any ASCII based tool … Read more
Use setRoundingMode, set the RoundingMode explicitly to handle your issue with the half-even round, then use the format pattern for your required output. Example: DecimalFormat df = new DecimalFormat(“#.####”); df.setRoundingMode(RoundingMode.CEILING); for (Number n : Arrays.asList(12, 123.12345, 0.23, 0.1, 2341234.212431324)) { Double d = n.doubleValue(); System.out.println(df.format(d)); } gives the output: 12 123.1235 0.23 0.1 2341234.2125 EDIT: … Read more
All Versions In case you happen to need just a single entry: There is Collections.singletonMap(“key”, “value”). For Java Version 9 or higher: Yes, this is possible now. In Java 9 a couple of factory methods have been added that simplify the creation of maps : // this works for up to 10 elements: Map<String, String> … Read more
You can add local dependencies directly (as mentioned in build maven project with propriatery libraries included) like this: <dependency> <groupId>com.sample</groupId> <artifactId>sample</artifactId> <version>1.0</version> <scope>system</scope> <systemPath>${project.basedir}/src/main/resources/Name_Your_JAR.jar</systemPath> </dependency> Update In new releases this feature is marked as deprecated but still working and not removed yet ( You just see warning in the log during maven start). An issue … Read more
Note that each of the code samples below may throw IOException. Try/catch/finally blocks have been omitted for brevity. See this tutorial for information about exception handling. Note that each of the code samples below will overwrite the file if it already exists Creating a text file: PrintWriter writer = new PrintWriter(“the-file-name.txt”, “UTF-8”); writer.println(“The first line”); … Read more
No, a null check is not needed before using instanceof. The expression x instanceof SomeClass is false if x is null. The Java 11 Language Specification expresses this concisely in section 15.20.2, “Type comparison operator instanceof”. (Java 17 expresses this less concisely, after the introduction of instanceof patternmatching.) “At run time, the result of the … Read more
I found a one-line solution from the good old Apache Commons Lang library. ArrayUtils.addAll(T[], T…) Code: String[] both = ArrayUtils.addAll(first, second);