java-8

问题 I just install jdk and jre version 8 In windows. Environment variable already set. I try run "java -version" in cmd and it shows the version of java installed. But when I try to compile java project with "javac projectName" system says javac is not recognized as internal or external command. So can anyone tell me how to fix it? here is my environment variable: C:\Users\Foody>echo %PATH% C:\ProgramData\Oracle\Java\javapath;C:\Program Files (x86)\NVIDIA Corporation\Ph ysX\Common;C:\WINDOWS

问题 I just install jdk and jre version 8 In windows. Environment variable already set. I try run "java -version" in cmd and it shows the version of java installed. But when I try to compile java project with "javac projectName" system says javac is not recognized as internal or external command. So can anyone tell me how to fix it? here is my environment variable: C:\Users\Foody>echo %PATH% C:\ProgramData\Oracle\Java\javapath;C:\Program Files (x86)\NVIDIA Corporation\Ph ysX\Common;C:\WINDOWS

问题 I was just searching for better way to handle this scenario using java 8 streams. Object A has list of object b. What I get is a list of object A (List). I need to stream through list of object A and get all the listB's in each of the object A as a one single list. class A { List<B> listB } I have tried the below way it throws compilation List<A> as = someObject.getAs(); List<B> listofBs = as.stream().map(in -> in.getListB()).collect(Collectors.toList()); 回答1: To get a single list of all B's,

问题 I have encountered a syntax problem in the following code used for Threading: btnNewButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e){ new Thread(() -> { GrabberShowUsesCallable gs = new GrabberShowUsesCallable(); //GrabberShow gs = new GrabberShow(); ExecutorService executorService = Executors.newSingleThreadExecutor(); Future<String> future = executorService.submit(gs); String cc; try { //Add data to table cc = future.get(); model.addRow(new Object[]

问题 I have encountered a syntax problem in the following code used for Threading: btnNewButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e){ new Thread(() -> { GrabberShowUsesCallable gs = new GrabberShowUsesCallable(); //GrabberShow gs = new GrabberShow(); ExecutorService executorService = Executors.newSingleThreadExecutor(); Future<String> future = executorService.submit(gs); String cc; try { //Add data to table cc = future.get(); model.addRow(new Object[]

问题 This question already has answers here : Java 8 Lambda function that throws exception? (26 answers) Closed 4 years ago . I have the following code snippet. package web_xtra_klasa.utils; import java.util.Arrays; import java.util.Properties; import java.util.function.Function; import javax.mail.Message; import javax.mail.MessagingException; import javax.mail.Session; import javax.mail.Transport; import javax.mail.internet.InternetAddress; import javax.mail.internet.MimeMessage; public class

问题 I'm a little confused using the DateTime related class for Java SE 7 and 8 API's, for displaying the current time, I'm reviewing the multiple ways for get the system's current datetime. My question is : Which one is more accurate for displaying time in millis? Next is the code snippet, I'm using Java 8 for the reviewing. import java.time.Instant; import java.util.Calendar; import java.util.Date; public class CurrentTimeValidationDemo { public static void main(String[] args) { Instant now =

问题 I'm a little confused using the DateTime related class for Java SE 7 and 8 API's, for displaying the current time, I'm reviewing the multiple ways for get the system's current datetime. My question is : Which one is more accurate for displaying time in millis? Next is the code snippet, I'm using Java 8 for the reviewing. import java.time.Instant; import java.util.Calendar; import java.util.Date; public class CurrentTimeValidationDemo { public static void main(String[] args) { Instant now =

问题 What is better in calling names.stream().forEach(System.out::println); Than names.stream().forEach(n -> System.out.println(n)); Despite the fact you have to write less code? Are there any other advantages of introducing method references in Java 8? 回答1: Despite the fact you have to write less code? Are there any other advantages of introducing method references in Java 8? Having to write less code is enough of an advantage to consider introducing a language feature. There is a similar feature

问题 I wanted to convert list to Map as below. Here is the example. I have student list something like below code snippet. Get a Hasmap out of it with Key as Integer which is Age and value as List. From the below input feed, My response should be something like below. How do I achieve this ? Map[[10, {1}], [20, {2,3,4}], [30,{5}]. [40,{6}]]; private static List<Person> getPersonTestData() { List<Person> personList = new ArrayList<>(); personList.add(Person.of(1, "First1", "Last1", 10)); personList