java 8 stream examples

.idea/.gitignore

+# Default ignored files
+/shelf/
+/workspace.xml

.idea/compiler.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="CompilerConfiguration">
+    <annotationProcessing>
+      <profile name="Maven default annotation processors profile" enabled="true">
+        <sourceOutputDir name="target/generated-sources/annotations" />
+        <sourceTestOutputDir name="target/generated-test-sources/test-annotations" />
+        <outputRelativeToContentRoot value="true" />
+        <module name="stream-api" />
+      </profile>
+    </annotationProcessing>
+  </component>
+</project>
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.idea/jarRepositories.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="RemoteRepositoriesConfiguration">
+    <remote-repository>
+      <option name="id" value="central" />
+      <option name="name" value="Central Repository" />
+      <option name="url" value="https://repo.maven.apache.org/maven2" />
+    </remote-repository>
+    <remote-repository>
+      <option name="id" value="central" />
+      <option name="name" value="Maven Central repository" />
+      <option name="url" value="https://repo1.maven.org/maven2" />
+    </remote-repository>
+    <remote-repository>
+      <option name="id" value="jboss.community" />
+      <option name="name" value="JBoss Community repository" />
+      <option name="url" value="https://repository.jboss.org/nexus/content/repositories/public/" />
+    </remote-repository>
+  </component>
+</project>
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.idea/misc.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ExternalStorageConfigurationManager" enabled="true" />
+  <component name="MavenProjectsManager">
+    <option name="originalFiles">
+      <list>
+        <option value="$PROJECT_DIR$/pom.xml" />
+      </list>
+    </option>
+  </component>
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" default="true" project-jdk-name="corretto-1.8" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+</project>
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pom.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.example</groupId>
+    <artifactId>stream-api</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <properties>
+        <maven.compiler.source>8</maven.compiler.source>
+        <maven.compiler.target>8</maven.compiler.target>
+    </properties>
+
+</project>
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src/main/java/StreamImpl.java

+// Implement stream examples with different variations.
+/*Intermediate Operations:
+filter() findFirst() flatmap() anyMath() skip() sorted() map() distinct()
+Terminal Operations:
+        ForEach()
+        collect()
+        Reduce operations:-
+        count()
+        max()
+        min()
+        average()
+        sum()
+        reduce()
+        summaryStatistics()*/
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public class StreamImpl {
+    public static void main(String[] args) {
+
+        // filter() method.
+        // Example 1
+//        int[] numbers = {1,2,3,4,5,6};
+        // primitive to wrapper type is boxing.
+        // wrapper to primitive is unboxing.
+//        Arrays.stream(numbers).boxed().filter(x -> x != 3).forEach(System.out::println);
+
+//        int[] myNumbers = IntStream.range(1,9).filter(x -> x != 3).toArray();
+//        System.out.println(Arrays.toString(myNumbers));
+
+//        // Example 2 Convert an array of string type numbers to int type.
+//        String[] stringNumbers = {"1","2","3","4","5","6"};
+//        int[] intNumbers = Arrays.stream(stringNumbers).mapToInt(Integer::parseInt).toArray();
+//        System.out.println(Arrays.toString(intNumbers));
+
+
+//        // Example 3 Convert array of primitive integers to List of Integers.
+//        int[] primitiveNumbers = {1,2,3,4,5,6};
+//        List<Integer> wrapperIntegers = Arrays.stream(primitiveNumbers).boxed().collect(Collectors.toList());
+//        System.out.println(wrapperIntegers);
+
+//        // Example 4 Mapping an array of string, replacing an element with its integer length.
+//        String[] words = {"Qadeer", "Naveed", "Adam", "Sam"};
+//        int[] wordLength = Arrays.stream(words).mapToInt(String::length).toArray();
+//        System.out.println(Arrays.toString(wordLength));
+
+
+//        // Example 5 Filter elements greater than a particular length.
+//        String[] words = {"Qadeer", "Naveed", "Adam", "Sam"};
+//        Object[] filteredWords = Arrays.stream(words).filter(s -> s.length() > 5).toArray();
+//        System.out.println(Arrays.toString(filteredWords));
+
+//        // Example 6 Convert array of primitive type to a List of Wrapper type.
+//        int[] array = {1,2,3,4,5,6};
+//        List<Integer> integerStream = IntStream.of(array).boxed().collect(Collectors.toList());
+//        System.out.println(integerStream);
+
+//        // Example 7
+//        List<Integer> number = Arrays.asList(1,2,3,4,5);
+//        int[] newNum = number.stream().mapToInt(Integer::intValue).toArray();
+//        System.out.println(Arrays.toString(newNum));
+
+//        // Example 8
+//        String[] words = {"Qadeer", "Naveed", "Bilal", "Ben", "Qabeer", "Qad", "steer", "butter"};
+//        Object[] filteredWords = Arrays.stream(words).filter(s -> s.startsWith("Qa")).filter(s -> s.endsWith("er")).toArray();
+//        System.out.println(Arrays.toString(filteredWords));
+    }
+}