Shifting array to the right – homework
You can do something like: I only modified your: letters.length-1 into letters.length-2 and printed the array. Another, easier approach is to use, System.arraycopy like: To print the array you can also use:
java
ConcurrentHashMap and Hashtable in Java
ConcurrentHashMap uses multiple buckets to store data. This avoids read locks and greatly improves performance over a HashTable. Both are thread safe, but there are obvious performance wins with ConcurrentHashMap. When you read from a ConcurrentHashMap using get(), there are no locks, contrary to the HashTable for which all operations are simply synchronized. HashTable was released in old versions of Java whereas ConcurrentHashMap is a java 5+ … Read more
If Java is Strongly typed then why does this code compile?
My understanding of strongly typed was that the language wouldn’t make implicit type conversions. However, this code converts the char to it’s ascii value and then uses that value.
What causes java.lang.IncompatibleClassChangeError?
This means that you have made some incompatible binary changes to the library without recompiling the client code. Java Language Specification §13 details all such changes, most prominently, changing non-static non-private fields/methods to be static or vice versa. Recompile the client code against the new library, and you should be good to go. UPDATE: If you publish a public library, … Read more
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘demoRestController’
Your DemoApplication class is in the com.ag.digital.demo.boot package and your LoginBean class is in the com.ag.digital.demo.bean package. By default components (classes annotated with @Component) are found if they are in the same package or a sub-package of your main application class DemoApplication. This means that LoginBean isn’t being found so dependency injection fails. There are a couple of ways to solve your problem: Move LoginBean into com.ag.digital.demo.boot or a sub-package. Configure … Read more
How to create a custom exception type in Java?
You should be able to create a custom exception class that extends the Exception class, for example: Usage:
Causes of getting a java.lang.VerifyError
java.lang.VerifyError can be the result when you have compiled against a different library than you are using at runtime. For example, this happened to me when trying to run a program that was compiled against Xerces 1, but Xerces 2 was found on the classpath. The required classes (in org.apache.* namespace) were found at runtime, so ClassNotFoundException was not the result. There … Read more
What is a safe way to create a Temp file in Java?
Use File.createTempFile(). Will create a file in the temp dir, like: prefix-6340763779352094442-suffix
How to solve javax.net.ssl.SSLHandshakeException Error?
First, you need to obtain the public certificate from the server you’re trying to connect to. That can be done in a variety of ways, such as contacting the server admin and asking for it, using OpenSSL to download it, or, since this appears to be an HTTP server, connecting to it with any browser, viewing … Read more
Error: ‘else’ without ‘if’
Remove the semicolon at the end of this line: And please, please use curly brackets! Java is not like Python, where indenting the code creates a new block scope. Better to play it safe and always use curly brackets – at least until you get some more experience with the language and understand exactly when you can omit them.