annotations

Scanning Java annotations at runtime

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Use org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider API A component provider that scans the classpath from a base package. It then applies exclude and include filters to the resulting classes to find candidates. ClassPathScanningCandidateComponentProvider scanner = new ClassPathScanningCandidateComponentProvider(<DO_YOU_WANT_TO_USE_DEFALT_FILTER>); scanner.addIncludeFilter(new AnnotationTypeFilter(<TYPE_YOUR_ANNOTATION_HERE>.class)); for (BeanDefinition bd : scanner.findCandidateComponents(<TYPE_YOUR_BASE_PACKAGE_HERE>)) System.out.println(bd.getBeanClassName());

How do I assert my exception message with JUnit Test annotation?

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You could use the @Rule annotation with ExpectedException, like this: @Rule public ExpectedException expectedEx = ExpectedException.none(); @Test public void shouldThrowRuntimeExceptionWhenEmployeeIDisNull() throws Exception { expectedEx.expect(RuntimeException.class); expectedEx.expectMessage(“Employee ID is null”); // do something that should throw the exception… System.out.println(“=======Starting Exception process=======”); throw new NullPointerException(“Employee ID is null”); } Note that the example in the ExpectedException docs is … Read more

@Nullable annotation usage

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It makes it clear that the method accepts null values, and that if you override the method, you should also accept null values. It also serves as a hint for code analyzers like FindBugs. For example, if such a method dereferences its argument without checking for null first, FindBugs will emit a warning.

Only using @JsonIgnore during serialization, but not deserialization

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Exactly how to do this depends on the version of Jackson that you’re using. This changed around version 1.9, before that, you could do this by adding @JsonIgnore to the getter. Which you’ve tried: Add @JsonIgnore on the getter method only Do this, and also add a specific @JsonProperty annotation for your JSON “password” field … Read more

JsonMappingException: No suitable constructor found for type [simple type, class ]: can not instantiate from JSON object

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So, finally I realized what the problem is. It is not a Jackson configuration issue as I doubted. Actually the problem was in ApplesDO Class: public class ApplesDO { private String apple; public String getApple() { return apple; } public void setApple(String apple) { this.apple = apple; } public ApplesDO(CustomType custom) { //constructor Code } … Read more

Should we @Override an interface’s method implementation?

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You should use @Override whenever possible. It prevents simple mistakes from being made. Example: class C { @Override public boolean equals(SomeClass obj){ // code … } } This doesn’t compile because it doesn’t properly override public boolean equals(Object obj). The same will go for methods that implement an interface (1.6 and above only) or override … Read more