java-8

问题 I am attempting to install ElasticSearch 5.1.1 on my windows 10 's laptop with java 8.111 installed. when I try to install Elastic search that triggers an error C:\Users\userName\Downloads\elasticsearch-5.1.1\elasticsearch-5.1.1>.\bin\elasticsearch Displays me that error message : Error: missing `server' JVM at `C:\Program Files (x86)\Java\jre1.8.0_111\bin\server\jvm.dll'. Please install or use the JRE or JDK that contains these missing components. I found a fix for that type of error with

问题 What do you think is better (with arguments, of course): Optional.ofNullable( userName ) .ifPresent( nonNullUserName -> header.setUser( createUser( nonNullUserName ) ) ); or header.setUser( userName == null ? createUser( userName ) : null ); The method createUser creates xml element and the intent of the whole peace of code is to set it in a SOAP request depending on presence of userName . The benefits of the first approach I see is the absence of useless operations, the code does one thing

问题 I need to check if a non-java process is running (by process name) inside a java program - very similar to the issue in Java - how to check whether another (non-Java) process is running on Linux. The solution is ok, but it still needs to open a system call process, and I'd like to avoid this. Is there a pure-java way to get a list of running processes on linux? 回答1: A possible solution might be explorer the proc entries. Indeed, this is how top and others gain access to the list of running

问题 I need to check if a non-java process is running (by process name) inside a java program - very similar to the issue in Java - how to check whether another (non-Java) process is running on Linux. The solution is ok, but it still needs to open a system call process, and I'd like to avoid this. Is there a pure-java way to get a list of running processes on linux? 回答1: A possible solution might be explorer the proc entries. Indeed, this is how top and others gain access to the list of running

问题 I've a piece of code that "split" a file in some chunks when find a start record. List<StringBuilder> list = new ArrayList<>(); StringBuilder jc = null; try (BufferedReader br = Files.newBufferedReader(Paths.get("")) { for (String line = br.readLine(); line != null; line = br.readLine()) { if (line.startsWith("REQ00")) { jc = new StringBuilder(); list.add(jc); } jc.append(line); } } catch (IOException e) { e.printStackTrace(); } Is there any way to "convert" this code into Java 8 Stream way ?

问题 I get this SO exception when building the workspace. !ENTRY org.eclipse.core.jobs 4 2 2014-06-27 16:01:29.327 !MESSAGE An internal error occurred during: "Rebuilding". !STACK 0 java.lang.StackOverflowError at org.eclipse.jdt.internal.compiler.lookup.ParameterizedTypeBinding.mentionsAny(ParameterizedTypeBinding.java:915) at org.eclipse.jdt.internal.compiler.lookup.ParameterizedTypeBinding.mentionsAny(ParameterizedTypeBinding.java:915) My workspace has a lot of projects, with a lot of compile

问题 I am provided with an api ( fnGrpc ) that performs a gRPC call and returns a ListenableFuture that resolves to some value v (the implementation of which is fixed and unmodifiable). I want to provide a helper function ( fnHelper ) that: does some transformational processing on the gRPC result and itself returns a ListenableFuture that resolves to the transformed value t1 . handles failure of the gRPC call, and returns some other value t2 instead of having fnHelper 's caller see an

问题 I am provided with an api ( fnGrpc ) that performs a gRPC call and returns a ListenableFuture that resolves to some value v (the implementation of which is fixed and unmodifiable). I want to provide a helper function ( fnHelper ) that: does some transformational processing on the gRPC result and itself returns a ListenableFuture that resolves to the transformed value t1 . handles failure of the gRPC call, and returns some other value t2 instead of having fnHelper 's caller see an

问题 As an example, I want to create an infinite stream of Groups of tens like this: 0=[0, 1, 2, 3, 4, 5, 6, 7, 8, 9] 1=[10, 11, 12, 13, 14, 15, 16, 17, 18, 19] 2=[20, 21, 22, 23, 24, 25, 26, 27, 28, 29] ... I want to use an inifinte stream of ints as an Input, which should then be grouped. If the first stream iterates 10 times the resulting stream should have iterated only once. My working, but not very elegant code looks like this: // create a stream from 0 (inclusive) to 100 (exclusive)

问题 I have a project that has started throwing this error when building in Android Studio or Gradle: com.android.tools.r8.ApiLevelException: MethodHandle.invoke and MethodHandle.invokeExact are only supported starting with Android O (--min-api 26) Now I assume that it's related to use of Java 8 features, perhaps a lambda, but the error message gives no clue as to where the problem lies - it could be my code or it could be a library. What's the best way to find out where the offending code is? It