解決Qt 5.12.5 執行報錯 qt.network.ssl: QSslSocket::connectToHostEncrypted: TLS initialization failed

阿新 • • 發佈：2020-07-23

集合

定義：物件的容器，實現了對物件的常用操作，類似陣列的功能。

和陣列的區別：

陣列的長度是固定的，集合長度不固定
陣列可以儲存基本型別和引用型別，集合只能儲存引用型別

位置：java.util.*

Collection體系集合

collection父介面使用

特點：代表一組任意型別的物件，無序，無下標，不能重複

public class Demo01 {
    public static void main(String[] args) {
        //建立集合
        Collection collection = new ArrayList();
        //新增元素
        collection.add("紅豆");
        collection.add("我願意");
        collection.add("旋木");
        collection.add("只愛陌生人");
        collection.add("幽蘭操");
        System.out.println("元素個數"+collection.size());
        System.out.println(collection);
        //刪除元素
        collection.remove("旋木");
        System.out.println("元素個數"+collection.size());
        System.out.println(collection);
        //遍歷元素
        //增強for迴圈
        System.out.println("==============使用增強for迴圈遍歷元素==============");
        for (Object o : collection) {
            System.out.println(o);
        }
        //專門用來遍歷集合的一種方式
        System.out.println("==============使用迭代器遍歷元素==============");
        //hasNext()有無下個元素 next()獲取下個元素 remove()刪除當前元素 迭代過程中不能使用collection.remove進行刪除
        Iterator iterator = collection.iterator();
        while (iterator.hasNext()){
            String string = (String) iterator.next();
            System.out.println(string);
            iterator.remove();
        }
        System.out.println("元素個數"+collection.size());
        //判斷
        System.out.println("==============判斷==============");
        System.out.println(collection.contains("旋木"));
    }
}

public class Couple {
    private int age;
    private String name;

    public Couple(int age, String name) {
        this.age = age;
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Couple ["+"name="+this.name+","+"age="+this.age+"]";
    }
}

public class Demo02 {
    public static void main(String[] args) {
        Collection collection = new ArrayList();
        //新增資料
        Couple c1 = new Couple(26,"AB");
        Couple c2 = new Couple(27,"CD");
        Couple c3 = new Couple(28,"EF");
        collection.add(c1);
        collection.add(c2);
        collection.add(c3);
        System.out.println(collection.size());
        System.out.println(collection.toString());
        //刪除資料
        //collection.remove(c1);
        //System.out.println(collection.size());
        //collection.clear();
        //System.out.println(collection.size());
        //遍歷
        for (Object o : collection) {
            System.out.println(o);
        }
        System.out.println("==============使用迭代器遍歷元素==============");
        //迭代器
        Iterator iterator = collection.iterator();
        int i = 0;
        while (iterator.hasNext()){
            System.out.println(i);
            Couple couple = (Couple) iterator.next();
            System.out.println(couple.toString());
            i++;
        }
        //判斷
        Couple c4 = new Couple(28,"EF");
        System.out.println(collection.contains(c4));
    }
}

List子介面

特點：有序，有下標，元素可重複

程式碼例項

public class Demo03 {
    public static void main(String[] args) {
        List list = new ArrayList<>();
        list.add("Apple");
        list.add("XiaoMi");
        list.add("HuaWei");
        System.out.println("元素個數"+list.size());
        System.out.println(list.toString());
        for (Object o : list) {
            System.out.println(o);
        }
        for (int i = 0;i<list.size();i++){
            System.out.println(list.get(i));
        }
        //listiterator可以向前也可以向後遍歷列表
        ListIterator listIterator = list.listIterator();
        while (listIterator.hasNext()){
            System.out.println(listIterator.nextIndex()+":"+listIterator.next());
        }
        System.out.println("=====逆序======");
        while (listIterator.hasPrevious()){
            System.out.println(listIterator.previousIndex()+":"+listIterator.previous());
        }
        //判斷
        System.out.println(list.contains("HuaWei"));
        System.out.println(list.isEmpty());
        //獲取位置
        System.out.println(list.indexOf("HuaWei"));
    }
}

List實現類

ArrayList

特點：陣列結構實現，查詢快、增刪慢；JDK1.2之後出現的，執行效率快，執行緒不安全

預設容量大小：10 如果沒有向集合中新增元素，那麼其大小為0；新增任意一個元素後，容量變成10；超過10就會擴容，每次擴容為前一次的1.5倍（newcapacity=oldcapacity右移一位+newcapacity）

elementData陣列用來存放元素

size實際元素個數

add()新增元素

public boolean add(E e) {
        ensureCapacityInternal(size + 1);  // Increments modCount!!
        elementData[size++] = e;
        return true;
    }
private static int calculateCapacity(Object[] elementData, int minCapacity) {
        if (elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA) {
            return Math.max(DEFAULT_CAPACITY, minCapacity);
        }
        return minCapacity;
    }
private void ensureCapacityInternal(int minCapacity) {
        ensureExplicitCapacity(calculateCapacity(elementData, minCapacity));
    }
private void ensureExplicitCapacity(int minCapacity) {
        modCount++;

        // overflow-conscious code
        if (minCapacity - elementData.length > 0)
            grow(minCapacity);
    }

程式碼例項

public class Couple {
    private int age;
    private String name;

    public Couple(int age, String name) {
        this.age = age;
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Couple ["+"name="+this.name+","+"age="+this.age+"]";
    }

    @Override
    public boolean equals(Object obj) {
        if (this==obj){
            return true;
        }
        if (obj==null){
            return false;
        }
        if (obj instanceof Couple){
            Couple couple = (Couple)obj;
            if (this.name.equals(couple.getName())&&this.age==couple.getAge()){
                return true;
            }
        }
        return false;
    }
}

public class Demo05 {
    public static void main(String[] args) {
        ArrayList arrayList = new ArrayList<>();
        Couple c1 = new Couple(16, "AB");
        Couple c2 = new Couple(17, "CD");
        Couple c3 = new Couple(18, "EF");
        arrayList.add(c1);
        arrayList.add(c2);
        arrayList.add(c3);
        System.out.println("the number og the segments is "+arrayList.size());
        System.out.println(arrayList);
        System.out.println(arrayList.toString());
        //arrayList.remove(0);//刪除之後，後面的元素會補上來
        //arrayList.remove(new Couple(16,"AB"));//方法重寫 從地址判斷 修改成為內容判斷
        //System.out.println(arrayList.get(0));
        //遍歷
        Iterator iterator = arrayList.iterator();
        while (iterator.hasNext()){
            System.out.println(iterator.next());
        }
        System.out.println("================列表迭代器順序==================");
        ListIterator listIterator = arrayList.listIterator();
        while (listIterator.hasNext()){
            System.out.println(listIterator.next());
        }
        System.out.println("================列表迭代器逆序==================");
        while (listIterator.hasPrevious()){
            System.out.println(listIterator.previous());
        }
        //判斷
        System.out.println(arrayList.contains(new Couple(16,"AB")));
    }
}

Vector

特點：陣列結構實現，查詢快，增刪慢；JDK1.0出現，執行效率慢，執行緒安全

程式碼例項：

public class Demo06 {
    public static void main(String[] args) {
        //建立集合
        Vector vector = new Vector();
        vector.add("Apple");
        vector.add("Banana");
        vector.add("Orange");
        vector.add("Strawberry");
        System.out.println("元素個數="+vector.size());
        //列舉器
        Enumeration en = vector.elements();
        while (en.hasMoreElements()){
            System.out.println(en.nextElement());
        }
    }
}

LinkedList

特點：連結串列結構實現，增刪快，查詢慢；

程式碼例項

public class Demo07 {
    //雙向連結串列
    public static void main(String[] args) {
        LinkedList linkedList = new LinkedList();
        Couple c1 = new Couple(1, "A");
        Couple c2 = new Couple(2, "B");
        Couple c3 = new Couple(3, "C");
        linkedList.add(c1);
        linkedList.add(c2);
        linkedList.add(c3);
        System.out.println("元素個數"+linkedList.size());
        System.out.println(linkedList);
        for (Object o : linkedList) {
            System.out.println(o);
        }
        Iterator iterator = linkedList.iterator();
        while (iterator.hasNext()){
            System.out.println(iterator.next());
        }
        ListIterator listIterator = linkedList.listIterator();
        while (listIterator.hasNext()){
            System.out.println(listIterator.next());
        }
        while (listIterator.hasPrevious()){
            System.out.println(listIterator.previous());
        }
        //獲取
        System.out.println(linkedList.indexOf(c1));
    }
}

泛型

Java泛型是JDK1.5中引入的一個新特性，其本質是引數化型別，把型別作為引數傳遞

常見形式有泛型類、泛型介面、泛型方法

語法：<T,...>T稱為型別佔位符，表示一種引用型別

好處：

提高程式碼的重用性
防止型別轉換異常，提高程式碼的安全性

泛型類

程式碼例項

//T是型別佔位符，表示一種引用型別，如果編寫多個，使用逗號隔開
public class MyGeneric <T>{
    //使用泛型T
    //建立變數，但是不能new一個變數，因為變數的型別不確定，不能例項化
    T t;
    //新增方法
    public void show(T t){
        System.out.println(t);
    }
    //使用泛型作為方法返回值
    public T getT(){
        return t;
    }
}

泛型介面

程式碼例項

public interface MyInterface <T>{
    String name = "Faye";
    //不能使用泛型定義靜態常量

    T server(T t);
}

public class MyInterfaceImpl implements MyInterface<String>{
    @Override
    public String server(String s) {
        System.out.println(s);
        return null;
    }
}

泛型類實現泛型介面

⬇

public class MyInterfaceImpl2<T> implements MyInterface <T> {
    @Override
    public T server(T t) {
        System.out.println(t);
        return null;
    }
}

泛型方法

public class MyGenericMethod {
    //泛型方法
    public void show(){
        System.out.println("普通方法");
    }
    public <T> void show2(T t){
        System.out.println(t+"泛型方法");
    }
}

public class TestGeneric {
    public static void main(String[] args) {
        MyGeneric<String> myGeneric = new MyGeneric<>();
        myGeneric.t = "hello";
        myGeneric.show("hello bitches");
        String str = myGeneric.getT();
        System.out.println(str);
        //泛型只能是引用型別，不同的泛型物件不能相互賦值

        MyGeneric<Integer> myGeneric1 = new MyGeneric<>();
        myGeneric1.t = 100;
        myGeneric1.show(200);
        MyInterfaceImpl myInterface = new MyInterfaceImpl();
        myInterface.server("????");
        MyInterfaceImpl2<String> myInterfaceImpl2 = new MyInterfaceImpl2<>();
        myInterfaceImpl2.server("!!!!!!");
        MyGenericMethod myGenericMethod = new MyGenericMethod();
        myGenericMethod.show2("傳遞的型別不用確定，寫啥是啥");
        myGenericMethod.show2(11927050);
        myGenericMethod.show2(11927050.1314);
    }
}

泛型集合

引數化型別、型別安全的集合，強制集合元素的型別必須一致。

特點：

編譯時即可檢查，而非執行時丟擲異常。
訪問時，不必型別轉換（拆箱）。
不同泛型之間引用不能相互賦值，泛型不存在多型

程式碼例項

public class Demo01 {
    public static void main(String[] args) {
        ArrayList<String> arrayList = new ArrayList<String>();
        arrayList.add("xxx");
        arrayList.add("yyy");
        for (String s : arrayList) {
            System.out.println(s);
        }
        Iterator<String> iterator = arrayList.iterator();
        while (iterator.hasNext()){
            System.out.println(iterator.next());
        }
    }
}

Set集合

set子介面

特點：無序、無下標、元素不可重複

方法：全部繼承自collection中的方法

程式碼例項

public class Book implements Comparable<Book>{
    private String name;
    private int price;

    public Book(String name, int price) {
        this.name = name;
        this.price = price;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getPrice() {
        return price;
    }

    public void setPrice(int price) {
        this.price = price;
    }
    @Override
    public int hashCode() {
        //31是一個質數，減少雜湊衝突，避免出現hashCode的撞車
        //31能夠提高執行效率：31*i = (i<<5)-i
        int n1 = this.name.hashCode();
        int n2 = this.price;
        final int prime = 31;
        int result = 1;
        result = prime*result + price;
        result = prime*result + ((name == null)? 0 : name.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this==obj){
            return true;
        }
        if (this == null){
            return false;
        }
        if (this instanceof Book){
            Book book = (Book)obj;
            if (this.name==book.getName()&&this.price==book.getPrice()){
                return true;
            }
        }
        return false;
    }

    @Override
    //先比較姓名 再比較年齡
    public int compareTo(Book o) {
        int n1 = this.name.compareTo(o.getName());
        int n2 = this.price-o.getPrice();
        return n1 == 0?n2:n1;
    }
}

public class Demo01 {
    public static void main(String[] args) {
        Set<String> set = new HashSet<String>();
        set.add("《海邊的卡夫卡》");
        set.add("《世界盡頭與冷酷仙境》");
        set.add("《且聽風吟》");
        set.add("《挪威的森林》");
        set.add("《刺殺騎士團長》");
        set.add("《刺殺騎士團長》");
        System.out.println(set.size());
        System.out.println(set);
        set.remove("《且聽風吟》");
        //遍歷
        System.out.println("==================增強for迴圈==================");
        for (String s : set) {
            System.out.print(s+" ");
        }
        System.out.println("");
        System.out.println("==================迭代器==================");

        Iterator iterator = set.iterator();
        while (iterator.hasNext()){
            System.out.print(iterator.next()+" ");
        }
        System.out.println("");
        System.out.println(set.contains("《且聽風吟》"));
    }
}

Set實現類：

1. HashSet：

基於HashCode實現元素不重複；當存入元素的HashCode相同的時候，會呼叫equals進行確認，如果結果為true，則拒絕後者的進入

儲存結構為雜湊表（陣列+單向連結串列）

儲存過程：根據hashcode計算儲存為止，如果位置為空，則直接儲存，如果不為空，則執行第二步

再執行equals方法，若為true，則認為是重複的，否則形成連結串列

程式碼例項

public class Demo03 {
    public static void main(String[] args) {
        HashSet<Book> bookHashSet = new HashSet<>();
        Book book1 = new Book("設計中的設計", 100);
        Book book2 = new Book("巨人的隕落", 800);
        Book book3 = new Book("我們這個世界的羊", 900);
        Book book4 = new Book("我們這個世界的羊", 900);
        bookHashSet.add(book1);
        bookHashSet.add(book2);
        bookHashSet.add(book3);
        bookHashSet.add(book4);
        bookHashSet.add(new Book("我們這個世界的羊", 900));
        System.out.println(bookHashSet.size());
        //bookHashSet.remove(new Book("我們這個世界的羊", 900));
        //System.out.println(bookHashSet.size());
        System.out.println(bookHashSet.contains(new Book("我們這個世界的羊", 900)));
    }
}

2. TreeSet：

給予排列順序實現元素不重複

實現了SortedSet介面，對集合元素自動排序；元素物件的型別必須實現Comparable介面，指定排序規則；通過Comparable方法確定是否為重複元素

public class Demo04 {
    public static void main(String[] args) {
        TreeSet<Book> treeSet = new TreeSet<>();
        Book book1 = new Book("設計中的設計", 100);
        Book book2 = new Book("巨人的隕落", 800);
        Book book3 = new Book("我們這個世界的羊", 900);
        Book book4 = new Book("我們這個世界的羊", 900);
        treeSet.add(book1);
        treeSet.add(book2);
        treeSet.add(book3);
        treeSet.add(book4);
        //元素必須實現comparable介面，compareTo()返回值為0的時候，認為是重複元素
        System.out.println(treeSet.size());
    }
}

//比較器實現定製比較
public class Demo05 {
    public static void main(String[] args) {
        //建立集合的時候就制定了比較規則，不用實現介面
        TreeSet<Book> treeSet = new TreeSet<>(new Comparator<Book>() {
            @Override
            public int compare(Book o1, Book o2) {
                int n1 = o1.getPrice()-o2.getPrice();
                int n2 = o1.getName().compareTo(o2.getName());
                return n1==0?n2:n1;
            }
        });
    }
}

練習程式碼

//使用TreeSet集合來實現字串按照長度進行排序
    //comparator介面
public class Demo06 {
    public static void main(String[] args) {
        TreeSet<String> treeSet = new TreeSet<>(new Comparator<String>() {
            @Override
            public int compare(String o1, String o2) {
                int n1 = o1.length()-o2.length();
                int n2 = o1.compareTo(o2);
                return n1==0?n2:n1;
            }
        });
        treeSet.add("abcd");
        treeSet.add("bcd");
        treeSet.add("ebcd");
        treeSet.add("abdd");

        Iterator<String> iterator = treeSet.iterator();
        while (iterator.hasNext()){
            System.out.println(iterator.next());
        }
    }
}

Map集合

Map父介面

特點：儲存一對資料（Key-Value），無序無下標、鍵不允許重複，值可以重複

程式碼例項

public class Demo01 {
    public static void main(String[] args) {
        Map<String, String> map = new HashMap<>();
        map.put("Cola","5");
        map.put("Spine","3.5");
        map.put("Soda","4.5");
        map.put("Soda","7");
        System.out.println(map.size());
        System.out.println(map.toString());
        //map.remove("Soda");
        System.out.println(map.toString());
        Set<String> keySet = map.keySet();
        for (String s : keySet) {
            System.out.println(s+"===="+map.get(s));
        }
        for (String s : map.keySet()) {
            System.out.println(s+"===="+map.get(s));
        }
        System.out.println("使用entryset方法");
        Set<Map.Entry<String, String>> entrySet = map.entrySet();
        for (Map.Entry<String, String> entry : entrySet) {
            System.out.println(entry.getKey()+"==="+entry.getValue());
        }
    }
}

Map實現類

public class Wechat implements Comparable{
    private String username;
    private int userage;

    public Wechat() {
    }

    public Wechat(String username, int userage) {
        this.username = username;
        this.userage = userage;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public int getUserage() {
        return userage;
    }

    public void setUserage(int userage) {
        this.userage = userage;
    }

    @Override
    public int hashCode() {
        int prime = 31;
        int result = 1;
        result = prime*this.getUsername().hashCode();
        result = prime*this.getUserage()+result;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj){
            return true;
        }
        if (obj == null){
            return false;
        }
        if (obj instanceof Wechat){
            Wechat wechat = (Wechat)obj;
            if (this.userage==wechat.getUserage()&&this.username==wechat.getUsername()){
                return true;
            }
        }
        return false;
    }
    @Override
    public int compareTo(Object o) {
        Wechat o1 = (Wechat)o;
        int n1 = this.username.compareTo(o1.getUsername());
        int n2 = this.userage-o1.getUserage();
        return n1 == 0?n2:n1;
    }
}

HashMap

JDK1.2版本執行緒不安全，執行效率快

1.1 當hashmap剛剛建立的時候，table是null，為了既省空間，當新增第一個元素的時候，table的容量調整為16

1.2 當元素個數大於閾值（16*0.75=12）的時候，會進行擴容，擴容為原來的兩倍，目的是減少調整元素的個數

1.3 jdk1.8 當每個連結串列的長度大於8，並且元素個數大於等於64的時候，會調整為紅黑樹，目的是提高執行效率

1.4 jdk1.8 當連結串列長度小於6時，調整成連結串列

1.5 jdk1.8 連結串列尾插入

程式碼例項

public class Demo01 {
    public static void main(String[] args) {
        Map<String, String> map = new HashMap<>();
        map.put("Cola","5");
        map.put("Spine","3.5");
        map.put("Soda","4.5");
        map.put("Soda","7");
        System.out.println(map.size());
        System.out.println(map.toString());
        //map.remove("Soda");
        System.out.println(map.toString());
        Set<String> keySet = map.keySet();
        for (String s : keySet) {
            System.out.println(s+"===="+map.get(s));
        }
        for (String s : map.keySet()) {
            System.out.println(s+"===="+map.get(s));
        }
        System.out.println("使用entryset方法");
        Set<Map.Entry<String, String>> entrySet = map.entrySet();
        for (Map.Entry<String, String> entry : entrySet) {
            System.out.println(entry.getKey()+"==="+entry.getValue());
        }

    }
}

public class Demo02 {
    public static void main(String[] args) {
        HashMap<Wechat, String> hashMap = new HashMap<>();
        //剛建立沒有新增元素的時候 table = null size = 0 目的是節省空間
        Wechat wechat1 = new Wechat("A", 20);
        Wechat wechat2 = new Wechat("B", 30);
        Wechat wechat3 = new Wechat("C", 40);
        Wechat wechat4 = new Wechat("D", 50);
        hashMap.put(wechat1,"China");
        hashMap.put(wechat2,"America");
        hashMap.put(wechat3,"Netherlands");
        hashMap.put(wechat4,"England");
        hashMap.put(new Wechat("A",20),"China");
        System.out.println(hashMap.size());
        //entryset方法遍歷陣列
        Set<Map.Entry<Wechat, String>> entrySet = hashMap.entrySet();
        for (Map.Entry<Wechat, String> stringEntry : entrySet) {
            System.out.println(stringEntry.toString());
        }
        //keySet方法遍歷陣列
        Set<Wechat> keySet = hashMap.keySet();
        for (Wechat wechat : hashMap.keySet()) {
            System.out.println(wechat);
        }
        for (Wechat wechat : keySet) {
            System.out.println(wechat);
        }

    }

}

HashTable

（目前用的比較少）JDK1.0版本執行緒安全執行效率慢不允許null作為key或者value

Properties

（HashTable的子類）要求key和value都是String，通常用於配置檔案的讀取

TreeMap

實現了SortedMap介面，可以對key自動排序

程式碼例項

public class Demo03 {
    public static void main(String[] args) {
        TreeMap<Wechat, String> treeMap = new TreeMap<>();
        Wechat wechat1 = new Wechat("A", 20);
        Wechat wechat2 = new Wechat("B", 30);
        Wechat wechat3 = new Wechat("C", 40);
        Wechat wechat4 = new Wechat("D", 50);
        Wechat wechat5 = new Wechat("D", 50);
        treeMap.put(wechat1,"China");
        treeMap.put(wechat2,"America");
        treeMap.put(wechat3,"Netherlands");
        treeMap.put(wechat4,"England");
        treeMap.put(wechat5,"England");
        System.out.println(treeMap.size());
        System.out.println("=================keyset=================");
        Set<Wechat> keySet = treeMap.keySet();
        for (Wechat wechat : keySet) {
            System.out.println(wechat+"==="+treeMap.get(wechat));
        }
        System.out.println("=================entryset=================");
        Set<Map.Entry<Wechat, String>> entrySet = treeMap.entrySet();
        for (Map.Entry<Wechat, String> stringEntry : entrySet) {
            System.out.println(stringEntry);
        }
    }
}

collections工具類

程式碼例項

public class Demo04 {
    public static void main(String[] args) {
        List<Integer> list = new ArrayList<>();
        list.add(20);
        list.add(27);
        list.add(19);
        list.add(69);
        list.add(2);
        list.add(2);
        list.add(4);
        list.add(2);
        //排序
        System.out.println("排序前："+list.toString());
        Collections.sort(list);
        System.out.println("排序後："+list.toString());
        //二分法查詢 注意二分法的規則以及可能出現的問題
        int i1 = Collections.binarySearch(list,12);
        int i2 = Collections.binarySearch(list,2);//注意二分查詢的規則 這裡容易出錯
        System.out.println(i1);
        System.out.println(i2);
        //複製 但是複製的操作要求兩個集合的大小一致
        List<Integer> list2 = new ArrayList<>();
        for (int i = 0; i < list.size(); i++) {
            list2.add(0);
        }
        Collections.copy(list2,list);
        System.out.println(list2);
        //逆序
        Collections.reverse(list);
        System.out.println(list);
        //shuffle打亂
        Collections.shuffle(list);
        System.out.println(list);
        //補充：list轉成陣列
        Integer[] array = list.toArray(new Integer[0]);
        System.out.println(array.length);
        //陣列轉成list
        String[] names = {"Jessica","Linda","Cherry","Sabrina"};
        List<String> list1 = Arrays.asList(names);
        //受限集合 不能刪除或者新增元素
        System.out.println(list1);
        //如果使用基本型別的話，會使得整個集合中只有一個元素，這個元素就是原來的陣列，因此需要使用包裝類
        Integer[] nums = {20,30,40,60,60};
        int[] nums2 = {20,30,40,60,60};
        List<Integer> list3 = Arrays.asList(nums);
        List<int[]> list4 = Arrays.asList(nums2);
        System.out.println(list3.size());
        System.out.println(list4.size());
    }
}