added functional interface

.idea/.gitignore

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

.idea/misc.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" default="true" project-jdk-name="1.8" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+</project>
\ No newline at end of file

.idea/modules.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/Java-functional-Interface.iml" filepath="$PROJECT_DIR$/Java-functional-Interface.iml" />
+    </modules>
+  </component>
+</project>
\ No newline at end of file

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+        <initial-values>
+          <property name="text" value="Button" />
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+        <initial-values>
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+        </initial-values>
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+        <default-constraints vsize-policy="0" hsize-policy="0" anchor="8" fill="0" />
+        <initial-values>
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+        </initial-values>
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+          <preferred-size width="150" height="-1" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JFormattedTextField" icon="/com/intellij/uiDesigner/icons/formattedTextField.svg" removable="false" auto-create-binding="true" can-attach-label="true">
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+      </item>
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+      </item>
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+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JComboBox" icon="/com/intellij/uiDesigner/icons/comboBox.svg" removable="false" auto-create-binding="true" can-attach-label="true">
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+          <preferred-size width="150" height="50" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JTabbedPane" icon="/com/intellij/uiDesigner/icons/tabbedPane.svg" removable="false" auto-create-binding="true" can-attach-label="false">
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+        </default-constraints>
+      </item>
+      <item class="javax.swing.JSplitPane" icon="/com/intellij/uiDesigner/icons/splitPane.svg" removable="false" auto-create-binding="false" can-attach-label="false">
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+          <preferred-size width="200" height="200" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JSpinner" icon="/com/intellij/uiDesigner/icons/spinner.svg" removable="false" auto-create-binding="true" can-attach-label="true">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1" />
+      </item>
+      <item class="javax.swing.JSlider" icon="/com/intellij/uiDesigner/icons/slider.svg" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="8" fill="1" />
+      </item>
+      <item class="javax.swing.JSeparator" icon="/com/intellij/uiDesigner/icons/separator.svg" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="6" hsize-policy="6" anchor="0" fill="3" />
+      </item>
+      <item class="javax.swing.JProgressBar" icon="/com/intellij/uiDesigner/icons/progressbar.svg" removable="false" auto-create-binding="true" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="0" fill="1" />
+      </item>
+      <item class="javax.swing.JToolBar" icon="/com/intellij/uiDesigner/icons/toolbar.svg" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="6" anchor="0" fill="1">
+          <preferred-size width="-1" height="20" />
+        </default-constraints>
+      </item>
+      <item class="javax.swing.JToolBar$Separator" icon="/com/intellij/uiDesigner/icons/toolbarSeparator.svg" removable="false" auto-create-binding="false" can-attach-label="false">
+        <default-constraints vsize-policy="0" hsize-policy="0" anchor="0" fill="1" />
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+        <default-constraints vsize-policy="6" hsize-policy="0" anchor="0" fill="2" />
+      </item>
+    </group>
+  </component>
+</project>
\ No newline at end of file

.idea/vcs.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>
\ No newline at end of file

Java-functional-Interface.iml

+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file

src/Lambda/Display.java

+package Lambda;
+
+public interface Display
+{
+    public abstract void hello();
+}

src/Lambda/FunctionalInterfaceExample.java

+package Lambda;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class FunctionalInterfaceExample {
+
+    public static void main(String[] args) {
+        List<Person> people = new ArrayList<>();
+        people.add(new Person("harshitha",1));
+        people.add(new Person("Sai",2));
+        people.add(new Person("anusha",4));
+
+        people.sort((person1,person2) -> {
+            return person1.getAge() - person2.getAge();
+        });
+        for(Person person: people){
+            System.out.println(person.getName()+ " " +person.getAge());
+        }
+
+    }
+}
+
+class Person{
+    private String name;
+    private int age;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public Person(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+}

src/Lambda/FunctionalTest.java

+package Lambda;
+
+public interface FunctionalTest {
+
+    void abstractTest(int x);
+
+    default void Message(){
+        System.out.println("hello");
+    }
+
+}
+
+class Test{
+    public static void main(String[] args) {
+
+        FunctionalTest functionalTest = (int x) -> System.out.println(2*x);
+        functionalTest.abstractTest(7);
+    }
+}

src/Lambda/PredicateExample.java

+package Lambda;
+
+public class PredicateExample {
+    public static void main(String[] args) {
+        Display i = () -> System.out.println("This is predicate example");
+        i.hello();
+
+        SumOfTwoIntegers s = (a, b) -> (a+b);
+        System.out.println(s.sum(5,6));
+        System.out.println(s.sum(7,7));
+    }
+}

src/Lambda/PredicateExample1.java

+package Lambda;
+
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.*;
+import java.util.function.Predicate;
+
+public class PredicateExample1 {
+
+    public static void main(String[] args) {
+        List<User> users = new ArrayList<User>();
+        users.add(new User("dev","Harshitha"));
+        users.add(new User("dev","yamini"));
+        users.add(new User("QA","Anusha"));
+
+        List devs = process(users,(User u)->u.getRole().equals("dev"));
+        System.out.println(devs);
+
+    }
+
+    public static  List<User> process(List<User> users, Predicate<User> predicate){
+        List<User> result = new ArrayList<User>();
+        for(User user:users){
+            if(predicate.test(user)){
+                result.add(user);
+            }
+        }
+        return  result;
+    }
+}
+

src/Lambda/PredicateStringComparing.java

+package Lambda;
+
+import java.util.function.Predicate;
+
+public class PredicateStringComparing {
+    public static void main(String[] args) {
+        String s1="hello";
+        String s2="hello";
+        Predicate<String> p = s->s.equals(s2);
+
+        if(p.test(s1)){
+            System.out.println("equal");
+        }
+        else{
+            System.out.println("not equal");
+        }
+
+    }
+}

src/Lambda/SumOfTwoIntegers.java

+package Lambda;
+
+public interface SumOfTwoIntegers
+{
+
+    public abstract int sum(int a,int b);
+}

src/Lambda/SupplierExample.java

+package Lambda;
+
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
+public class SupplierExample {
+    public static void main(String[] args) {
+
+
+        //example of supplier
+        Supplier<String> supplier = () -> {
+            System.out.println("inside the supplier");
+            return  "hello";
+        };
+        String string = supplier.get();
+        System.out.println(string);
+
+
+        //example of consumer
+        Consumer<String> consumer = (String s) -> {
+            System.out.println("Inside the consumer");
+            System.out.println(s);
+        };
+        consumer.accept("hello");
+
+        Supplier<String> supplier1 = () -> {
+            System.out.println("Supplier");
+            return "hello";
+        };
+        String s = supplier1.get();
+        System.out.println(s);
+    }
+}

src/Lambda/User.java

+package Lambda;
+
+
+public class User {
+
+    private String role;
+    private String name;
+
+    public String getRole() {
+        return role;
+    }
+
+    public void setRole(String role) {
+        this.role = role;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    @Override
+    public String toString() {
+        return "User{" +
+                "role='" + role + '\'' +
+                ", name='" + name + '\'' +
+                '}';
+    }
+
+    public User(String role, String name) {
+        this.role = role;
+        this.name = name;
+    }
+}

src/Main.java

+public class Main {
+    public static void main(String[] args) {
+        System.out.println("Hello world!");
+    }
+}
\ No newline at end of file