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Test if object implements interface
... work in a NullPointerException safe way. For example:
if ("" instanceof java.io.Serializable) {
// it's true
}
yields true. Since:
if (null instanceof AnyType) {
// never reached
}
yields false, the instanceof operator is null safe (the code you posted isn't).
instanceof is th...
How do I create a datetime in Python from milliseconds?
I can create a similar Date object in Java by java.util.Date(milliseconds) . How do I create the comparable in Python?
5 A...
Why do == comparisons with Integer.valueOf(String) give different results for 127 and 128?
...h, it appears that the questioner did not understand an underlying fact in Java: When using "==" to compare two objects, you are testing if they are references to the same object. When using "equals()", you are testing if they have the same value. You cannot use "equals" to compare primitives.
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Fetch first element which matches criteria
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@iammrmehul No. findFirst() returns an Optional object (JavaDoc), which might be empty. In this case the call to get() will throw the NPE. To prevent that from happening, use orElse() instead of get() and provide a fallback object (like orElse(new Station("dummy", -1)), or store t...
How do I find out if first character of a string is a number?
In Java is there a way to find out if first character of a string is a number?
5 Answers
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Check a collection size with JSTL
...u'll need JSTL fn:length() function then. From the documentation:
length( java.lang.Object) - Returns the number of items in a collection, or the number of characters in a string.
Put this at the top of JSP page to allow the fn namespace:
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl...
How to add reference to a method parameter in javadoc?
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As far as I can tell after reading the docs for javadoc there is no such feature.
Don't use <code>foo</code> as recommended in other answers; you can use {@code foo}. This is especially good to know when you refer to a generic type such as {@code Iterator<...
Logging framework incompatibility
I'm building a small Java app and hoping to use logback for logging.
3 Answers
3
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How to use conditional breakpoint in Eclipse?
...rties.
In the dialog box, check Enable Condition, and enter an arbitrary Java
condition, such as list.size()==0. Now, each time the breakpoint is
reached, the expression is evaluated in the context of the breakpoint
execution, and the breakpoint is either ignored or honored, depending
on t...
How to do an instanceof check with Scala(Test)
I'm trying to incorporate ScalaTest into my Java project; replacing all JUnit tests with ScalaTests. At one point, I want to check if Guice's Injector injects the correct type. In Java, I have a test like this:
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