Examples for java stream api

java-8/stream-api/ExampleStreamCreation.java

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+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.*;
+import java.util.regex.Pattern;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
+class ExampleStreamCreation {
+    public static void main(String[] args) {
+        //Stream from values
+        Stream stream = Stream.of(1);
+        Stream<Character> charStream = Stream.of('a', 'b', 'c');
+        Stream<String> strStream = Stream.of("Hello", "World");
+
+        //Stream from a string
+        IntStream intStream = "Hello World !!".chars();
+        IntStream intStream1 = "Hello World !!".codePoints();
+
+        //stream from pattern
+        Pattern p = Pattern.compile(",");
+        StringBuilder stringBuilder = new StringBuilder("1,2,3,4,5");
+        Stream<String> patternStream = p.splitAsStream(stringBuilder);
+
+        //stream from array
+        Stream<Integer> intStream2 = Stream.of(new Integer[]{1, 2, 3, 4, 5});
+        IntStream intStream3 = Arrays.stream(new int[]{1, 2, 3, 4});
+
+        int[] mainArray = new int[]{1, 2, 3, 4, 5, 6, 7};
+        IntStream s = Arrays.stream(mainArray, 2, 5);
+
+        //stream from collection
+        List<String> wordList = new ArrayList<>();
+        wordList.add("Hello");
+        wordList.add("World");
+
+        Stream wordStream = wordList.stream();
+        Stream parallelWordStream = wordList.parallelStream();
+
+        //from a set
+        Set set = new HashSet();
+        set.add("First element");
+        set.add("Second element");
+        set.add("Third element");
+
+        Stream setStream = set.stream();
+
+        //empty stream
+        Stream emptyStream = Stream.empty();
+        Stream emptyStream1 = Stream.of();
+
+        //from generate
+        Stream.generate(new Random()::nextInt).limit(6).forEach(System.out::println);
+
+        //from iterate
+        Stream.iterate(3, n -> n + 1).limit(6).forEach(System.out::println);
+
+        //from file
+        try {
+            Stream<String> fileStream = Files.lines(Paths.get("C:\\sample.txt"));
+            fileStream.forEach(System.out::println);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+        try {
+            Optional<String> lineWithStreamWord = Files.lines(Paths.get("C:\\sample.txt")).filter(s1 -> s1.contains("stream")).findFirst();
+            if (lineWithStreamWord.isPresent()) {
+                System.out.println(lineWithStreamWord.get());
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+}