Find first element by predicate

2021-6-3 anglehua

I've just started playing with Java 8 lambdas and I'm trying to implement some of the things that I'm used to in functional languages. For example, most functional languages have some kind of find function that operates on sequences, or lists that returns the first element, for which the predicate i...

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How to convert Java String into byte[]?

2021-6-3 anglehua

Is there any way to convert Java String to a byte[] (not the boxed Byte[])? In trying this: System.out.println(response.split("\r\n\r\n")[1]); System.out.println("******"); System.out.println(response.split("\r\n\r\n")[1].getBytes().toString()); and I'm getting separate outputs. Unable to display 1...

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Get generic type of class at runtime

2021-6-3 anglehua

How can I achieve this? public class GenericClass<T> { public Type getMyType() { //How do I return the type of T? } } Everything I have tried so far always returns type Object rather than the specific type used. As others mentioned, it's only possible via reflection in ce...

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Eclipse: Set maximum line length for auto formatting?

2021-6-3 anglehua

I am working with Java. If I hit Ctrl+Shift+F in Eclipse Helios, it will auto format my code. At a certain point, it wraps lines. I would like to increase the maximum line length. How can I do this? In preferences Java -> Code Style -> Formatter, edit the profile. Under the Line Wrapping tab ...

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View's getWidth() and getHeight() returns 0

2021-6-3 anglehua

I am creating all of the elements in my android project dynamically. I am trying to get the width and height of a button so that I can rotate that button around. I am just trying to learn how to work with the android language. However, it returns 0. I did some research and I saw that it needs to be...

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How to call a SOAP web service on Android

2021-6-3 anglehua

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 3 years ago. ...

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IllegalArgumentException or NullPointerException for a null parameter?

2021-6-3 anglehua

Closed. This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 4 years ago. ...

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Multiple line code example in Javadoc comment

2021-6-3 anglehua

I have a small code example I want to include in the Javadoc comment for a method. /** * -- ex: looping through List of Map objects -- * <code> * for (int i = 0; i < list.size(); i++) { * Map map = (Map)list.get(i); * System.out.println(map.get("wordID")); * System.ou...

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JPA JoinColumn vs mappedBy

2021-6-3 anglehua

What is the difference between: @Entity public class Company { @OneToMany(cascade = CascadeType.ALL , fetch = FetchType.LAZY) @JoinColumn(name = "companyIdRef", referencedColumnName = "companyId") private List<Branch> branches; ... } and @Entity public class Company { @O...

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Does anyone have benchmarks (code & results) comparing performance of Android apps written in Xamarin C# and Java?

2021-6-3 anglehua

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 3 years ago. ...

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How do I get a platform-dependent new line character?

2021-6-3 anglehua

How do I get a platform-dependent newline in Java? I can’t use "\n" everywhere. In addition to the line.separator property, if you are using java 1.5 or later and the String.format (or other formatting methods) you can use %n as in Calendar c = ...; String s = String.format("Duke's Birthday: %1$tm ...

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“PKIX path building failed” and “unable to find valid certification path to requested target”

2021-6-3 anglehua

I'm trying to get tweets using twitter4j library for my java project which uses under the covers java.net.HttpURLConnection (as can be seen in stack trace). On my first run I got an error about certificate sun.security.validator.ValidatorException and sun.security.provider.certpath.SunCertPathBuilde...

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How do I “decompile” Java class files?

2021-6-3 anglehua

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 5 years ago. Loc...

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When would you use the Builder Pattern?

2021-6-3 anglehua

Closed. This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 6 years ago. ...

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Why is there no SortedList in Java?

2021-6-3 anglehua

In Java there are the SortedSet and SortedMap interfaces. Both belong to the Java Collections framework and provide a sorted way to access the elements. However, in my understanding there is no SortedList in Java. You can use java.util.Collections.sort() to sort a list. Any idea why it is designed ...

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Why doesn't Java allow overriding of static methods?

2021-6-3 anglehua

Why is it not possible to override static methods? If possible, please use an example. Overriding depends on having an instance of a class. The point of polymorphism is that you can subclass a class and the objects implementing those subclasses will have different behaviors for the same methods def...

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How to determine an object's class?

2021-6-3 anglehua

If class B and class C extend class A and I have an object of type B or C, how can I determine of which type it is an instance? if (obj instanceof C) { //your code } Use Object.getClass(). It returns the runtime type of the object. 采集自互联网,如有侵权请联系本人

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Where does the @Transactional annotation belong?

2021-6-3 anglehua

Should you place the @Transactional in the DAO classes and/or their methods or is it better to annotate the Service classes which are calling using the DAO objects? Or does it make sense to annotate both "layers"? I think transactions belong on the Service layer. It's the one that knows about unit...

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ArithmeticException: “Non-terminating decimal expansion; no exact representable decimal result”

2021-6-3 anglehua

Why does the following code raise the exception shown below? BigDecimal a = new BigDecimal("1.6"); BigDecimal b = new BigDecimal("9.2"); a.divide(b) // results in the following exception. Exception: java.lang.ArithmeticException: Non-terminating decimal expansion; no exact representable decimal res...

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How does autowiring work in Spring?

2021-6-3 anglehua

I'm a little confused as to how the inversion of control (IoC) works in Spring. Say I have a service class called UserServiceImpl that implements UserService interface. How would this be @Autowired? And in my Controllers, how would I instantiate an instance of this service? Would I just do the follo...

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