By setting an object to null, we marks it as able to be garbage collected. But to avoid bad surprises, we should also clear the collections. With a collections being part of java.util package, we can ...
Sometimes we need to get the last element of the line. We can do it by mesuring the line length and getting the character through String's charAt(int) method. However, we can rarely deal with the Stri...
The difference is hidden under the "s" which is missing in the first method. In fact, mkdir() will create only demanded directory. If some of parent directories doesn't exist, this method will return ...
Making a screenshot in Java is quite simple thanks to java.awt package with a lot of graphical tools. First, take a look at the sample code: public class ScreenshotTest { @Test public void te...
By default, TreeMap stores the entries in ascending logic, from the smallest key to the biggest. Take a look on this sample: @Test public void normalTreeMap() { Map<String, String> alphabet =...
Java's array concatenation is always as simple as in PHP with array_merge method. In Java we need to use System.arraycopy() or org.apache.commons.lang.ArrayUtils.addAll() method. There are the code sa...
Sometimes we can use static imports instead of normal imports in Java. We can do that, for example, for JUnit assertions as assertTrue or assertFalse. We can also use it for some of java.lang.Math com...
Sometimes you can meet a strange java.lang.UnsupportedClassVersionError exception. As we can read at Javadoc, this exceptions is thrown when the JVM's JDK doesn't support JDK used to compile the class...
Imagine a for loop iterated 20 times and an array containing only 5 elements. How we can ensure that all elements will be printed inside the loop exactly 4 times ? Take a look on following sample: ...
You can't generate JSP code programmatically, for example given String "<% include file="template.jsp" %>", and use it directly in the JSP. In our case, this code won't include template.jsp, but on...
Arrays.asList method is used to returns an instance of List directly from given array. However, this instance is fixed-size and it means that you can't modify the List structure by adding one more ele...
Enum in Java behaves like normal classes. So they can be abstract. In the case of abstract methods, enum entries need to define methods behaviour: public class EnumTest { private static enum N...
No. This is a prof: @Test public void should_not_throw_any_exception_on_casting_null_object() { DecimalFormat tested = null; Serializable castedTested = tested; assertThat(castedTested)...
Immutable collections can be constructed with a set of singleton* methods: sinleton for a Set, singletonMap for a Map and singletonList for a List: @Test public void should_correctly_create_single...
