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niumooniumoo
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feat: add java collection demo
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‎core-java-modules/core-java-base/src/main/java/com/wdbyte/collection/CollectionTest.java‎

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package com.wdbyte.collection;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* @author niulang
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*/
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public class CollectionTest {
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public static void main(String[] args) {
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List<String> arrayList = new ArrayList<>();
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// 向 List 中添加元素
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arrayList.add("www");
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arrayList.add("wdbyte");
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arrayList.add("com");
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arrayList.add("com");
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// 输出
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System.out.println(arrayList);
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}
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}

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/collection/CollectionTest2.java‎

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package com.wdbyte.collection;
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import java.util.ArrayList;
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import java.util.HashSet;
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import java.util.LinkedList;
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import java.util.List;
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import java.util.Set;
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import java.util.Stack;
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import java.util.TreeSet;
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/**
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* @author niulang
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*/
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public class CollectionTest2 {
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public static void main(String[] args) {
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List<String> arrayList = new ArrayList<>();
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List<String> linkedList = new LinkedList<>();
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Set<String> hashSet = new HashSet<>();
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Set<String> treeSet = new TreeSet<>();
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Stack<String> stack = new Stack<>();
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// 添加元素
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arrayList.add("wdbyte.com");
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linkedList.add("wdbyte.com");
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hashSet.add("wdbyte.com");
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treeSet.add("wdbyte.com");
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stack.add("wdbyte.com");
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// 输出
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System.out.println(arrayList);
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System.out.println(linkedList);
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System.out.println(hashSet);
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System.out.println(treeSet);
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System.out.println(stack);
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}
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}

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/collection/CollectionTest3.java‎

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package com.wdbyte.collection;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.List;
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/**
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* @author niulang
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*/
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public class CollectionTest3 {
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public static void main(String[] args) {
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List<String> arrayList = new ArrayList<>();
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// 向 List 中添加元素
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arrayList.add("www");
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arrayList.add("wdbyte");
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arrayList.add("com");
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// 普通遍历
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for (int i = 0; i < arrayList.size(); i++) {
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System.out.println(arrayList.get(0));
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}
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System.out.println("--------");
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// iterator 迭代器遍历
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Iterator<String> iterator = arrayList.iterator();
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while (iterator.hasNext()) {
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System.out.println(iterator.next());
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}
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}
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public void printCollection(Collection collection) {
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for (Object o : collection) {
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System.out.println(o);
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}
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}
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}

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/collection/CollectionTest4.java‎

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package com.wdbyte.collection;
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import java.time.LocalDate;
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import java.util.ArrayList;
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import java.util.HashSet;
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import java.util.Iterator;
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import java.util.List;
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/**
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* @author niulang
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*/
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public class CollectionTest4 {
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public static void main(String[] args) {
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List<String> arrayList = new ArrayList<>();
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// 向 List 中添加元素
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arrayList.add("www");
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arrayList.add("wdbyte");
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arrayList.add("com");
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HashSet<String> hashSet = new HashSet<>();
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hashSet.addAll(arrayList);
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printCollection(arrayList.iterator());
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System.out.println("--------------");
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printCollection(hashSet.iterator());
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}
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public static void printCollection(Iterator<String> iterator) {
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// 当前日期
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LocalDate now = LocalDate.now();
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while (iterator.hasNext()) {
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String obj = iterator.next();
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System.out.println(now + ":" + obj.toString());
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}
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}
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}

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/collection/CollectionTest5.java‎

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package com.wdbyte.collection;
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import java.time.LocalDate;
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import java.util.ArrayList;
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import java.util.HashSet;
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import java.util.Iterator;
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import java.util.List;
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/**
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* @author niulang
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*/
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public class CollectionTest5 {
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public static void main(String[] args) {
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List<String> arrayList = new ArrayList<>();
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// 向 List 中添加元素
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arrayList.add("www");
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arrayList.add("wdbyte");
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arrayList.add("com");
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HashSet<String> hashSet = new HashSet<>();
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hashSet.addAll(arrayList);
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printCollection(arrayList);
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printCollection(hashSet);
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}
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public static void printCollection(Iterable<String> iterable) {
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// 当前日期
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LocalDate now = LocalDate.now();
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Iterator<String> iterator = iterable.iterator();
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while (iterator.hasNext()) {
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String obj = iterator.next();
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System.out.println(now + ":" + obj.toString());
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}
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}
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}

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/collection/MapTest.java‎

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package com.wdbyte.collection;
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import java.util.HashMap;
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import java.util.Map;
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/**
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* @author niulang
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*/
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public class MapTest {
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public static void main(String[] args) {
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Map<String, String> hashMap = new HashMap<>();
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// 添加元素
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hashMap.put("site","www.wdbyte.com");
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hashMap.put("author","程序猿阿朗");
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hashMap.put("github","github.com/niumoo");
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// 获取元素
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System.out.println(hashMap.get("github"));
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// 输出全部元素
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System.out.println(hashMap);
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}
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}

‎core-java-modules/core-java-base/src/main/java/com/wdbyte/collection/MapTest2.java‎

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package com.wdbyte.collection;
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import java.util.HashMap;
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import java.util.LinkedHashMap;
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import java.util.Map;
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/**
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* @author niulang
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*/
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public class MapTest2 {
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public static void main(String[] args) {
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Map<String, String> hashMap = new HashMap<>();
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Map<String, String> linkedHashMap = new LinkedHashMap<>();
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// 添加元素
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hashMap.put("site", "www.wdbyte.com");
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hashMap.put("author", "程序猿阿朗");
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hashMap.put("github", "github.com/niumoo");
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linkedHashMap.put("site", "www.wdbyte.com");
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linkedHashMap.put("author", "程序猿阿朗");
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linkedHashMap.put("github", "github.com/niumoo");
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// 输出全部元素
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System.out.println(hashMap);
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System.out.println(linkedHashMap);
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}
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}

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