Collectors partitioningBy example

Author: arpitaggarwal

src/main/java/com/test/so/solutions/PassFunctionAsAFunction.java

@@ -0,0 +1,36 @@
+package com.test.so.solutions;
+
+import java.util.LinkedList;
+import java.util.List;
+import java.util.function.Function;
+
+public class PassFunctionAsAFunction {
+
+	public void pass() {
+		run(() -> System.out.println("Hello world"));
+	}
+
+	public void run(Runnable function) {
+		function.run();
+	}
+
+	/**
+ * 
+ */
+	// Here I want to store the method references
+	List<Function> listOfMethodsToExecute = new LinkedList<>();
+
+	// Add a new function to the list
+	public void addFunction(Function f) {
+		if (f != null) {
+			listOfMethodsToExecute.add(f);
+		}
+	}
+
+	// Executes all the methods previously stored on the list
+	public void executeAll() {
+		listOfMethodsToExecute.stream().forEach((Function function) -> {
+			function.apply(null);
+		});
+	}
+}

src/main/java/com/test/so/solutions/SplitString.java

@@ -0,0 +1,52 @@
+package com.test.so.solutions;
+
+import java.util.Map;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class SplitString {
+
+	public static void main(String[] args) {
+		String str = "2014@2@200@0#2014@2@200@0#2012@2@200@0#2012@2@200@0#2011@2@200@0";
+		Map<String, TestClass> map = Stream.of(str.split("#")).map(e -> e.split("@")).map(x -> new TestClass(x[1], x[2], x[3], x[0])).collect(Collectors.toMap(TestClass::getA4, z -> z,(p1, p2) -> p1));
+		System.out.println(map);
+	}
+}
+
+class TestClass {
+
+	private final String a1;
+	private final String a2;
+	private final String a3;
+	private final String a4;
+
+	public TestClass(String a1, String a2, String a3, String a4) {
+		this.a1 = a1;
+		this.a2 = a2;
+		this.a3 = a3;
+		this.a4 = a4;
+	}
+
+	public String getA1() {
+		return a1;
+	}
+
+	public String getA2() {
+		return a2;
+	}
+
+	public String getA3() {
+		return a3;
+	}
+
+	public String getA4() {
+		return a4;
+	}
+
+	@Override
+	public String toString() {
+		return "TestClass [a4=" + a4 + ", a1=" + a1 + ", a2=" + a2 + ", a3="
+				+ a3 + "]";
+	}
+
+}

src/main/java/com/test/streams/GroupingBy.java

@@ -25,35 +25,3 @@ private static List<Student> getStudentList() {
 	}
 }
 
-class Student {
-	private final String teacher;
-	private final double level;
-	private final String className;
-
-	public Student(final String teacher, final double level,
-			final String className) {
-		super();
-		this.teacher = teacher;
-		this.level = level;
-		this.className = className;
-	}
-
-	public String getTeacher() {
-		return teacher;
-	}
-
-	public double getLevel() {
-		return level;
-	}
-
-	public String getClassName() {
-		return className;
-	}
-
-	@Override
-	public String toString() {
-		return "Student [teacher=" + teacher + ", level=" + level
-				+ ", className=" + className + "]";
-	}
-
-}

src/main/java/com/test/streams/PartitioningBy.java

@@ -0,0 +1,26 @@
+package com.test.streams;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+public class PartitioningBy {
+
+	public static void main(String[] args) {
+		Map<Boolean, List<Student>> partitioningByLevel = getStudentList().stream()
+				.collect(Collectors.partitioningBy(e -> e.getLevel()>101));
+		System.out.println(partitioningByLevel);
+	}
+
+	private static List<Student> getStudentList() {
+		List<Student> studentList = new ArrayList<>();
+
+		studentList.add(new Student("A", 101, "Intro to Web"));
+		studentList.add(new Student("B", 102, "Advanced Java"));
+		studentList.add(new Student("C", 101, "Intro to Cobol"));
+		studentList.add(new Student("A", 101, "Intro to Web"));
+		studentList.add(new Student("B", 102, "Advanced Web"));
+		return studentList;
+	}
+}

src/main/java/com/test/streams/Student.java

@@ -0,0 +1,35 @@
+package com.test.streams;
+
+public class Student {
+
+	private final String teacher;
+	private final double level;
+	private final String className;
+
+	public Student(final String teacher, final double level,
+			final String className) {
+		super();
+		this.teacher = teacher;
+		this.level = level;
+		this.className = className;
+	}
+
+	public String getTeacher() {
+		return teacher;
+	}
+
+	public double getLevel() {
+		return level;
+	}
+
+	public String getClassName() {
+		return className;
+	}
+
+	@Override
+	public String toString() {
+		return "Student [teacher=" + teacher + ", level=" + level
+				+ ", className=" + className + "]";
+	}
+
+}