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Commit 0098013

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Arpit Bhardwaj
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‎.gitignore‎

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# Project exclude paths
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/target/

‎pom.xml‎

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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<groupId>groupId</groupId>
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<artifactId>Generics</artifactId>
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<version>1.0-SNAPSHOT</version>
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<dependencies>
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<dependency>
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<groupId>junit</groupId>
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<artifactId>junit</artifactId>
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<version>4.11</version>
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</dependency>
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</dependencies>
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<build>
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<plugins>
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<plugin>
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<groupId>org.apache.maven.plugins</groupId>
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<artifactId>maven-compiler-plugin</artifactId>
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<version>3.7.0</version>
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<configuration>
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<source>1.8</source>
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<target>1.8</target>
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</configuration>
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</plugin>
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</plugins>
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</build>
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</project>

‎src/main/java/com/ab/generics/basic/CircularBuffer.java‎

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package com.ab.generics.basic;
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public class CircularBuffer {
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private Object[] buffer;
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private int readCursor = 0;
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private int writeCursor = 0;
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public CircularBuffer(int size) {
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this.buffer = new Object[size];
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}
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public boolean offer(Object value){
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if(buffer[writeCursor] != null){
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return false;
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}
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buffer[writeCursor] = value;
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writeCursor = next(writeCursor);
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return true;
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}
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public Object poll(){
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Object value = buffer[readCursor];
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if(value != null){
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buffer[readCursor] = null;
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readCursor = next(readCursor);
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}
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return value;
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}
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public int next(int index){
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return (index+1)%buffer.length;
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}
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}

‎src/main/java/com/ab/generics/basic/TypeUnsafeExample.java‎

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package com.ab.generics.basic;
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public class TypeUnsafeExample {
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public static void main(String[] args) {
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CircularBuffer buffer = new CircularBuffer(10);
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buffer.offer("a");
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buffer.offer("bc");
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buffer.offer("d");
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String value = concatenate(buffer);
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System.out.println(value);
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}
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private static String concatenate(CircularBuffer buffer) {
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StringBuilder result = new StringBuilder();
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String value;
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while((value = (String) buffer.poll()) != null){
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result.append(value);
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}
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return result.toString();
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}
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}

‎src/test/java/com/ab/generics/basic/CircularBufferTest.java‎

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package com.ab.generics.basic;
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import org.junit.Test;
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import static org.junit.Assert.*;
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public class CircularBufferTest {
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private CircularBuffer buffer = new CircularBuffer(2);
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@Test
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public void shouldOfferPollableElement() {
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assertTrue(buffer.offer(1));
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assertEquals(1,buffer.poll());
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assertNull(buffer.poll());
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}
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@Test
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public void shouldNotOfferWhenBufferIsFull() {
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assertTrue(buffer.offer(1));
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assertTrue(buffer.offer(2));
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assertFalse(buffer.offer(3));
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}
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@Test
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public void shouldNotPollWhenBufferIsEmpty(){
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assertNull(buffer.poll());
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}
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@Test
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public void shouldRecycleBuffer(){
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assertTrue(buffer.offer(1));
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assertTrue(buffer.offer(2));
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assertEquals(1,buffer.poll());
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assertTrue(buffer.offer(3));
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assertEquals(2,buffer.poll());
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assertEquals(3,buffer.poll());
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}
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}

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