在本篇文章中，將介紹5種創建Java對象的方式。類是創建對象的基本模板，接下來將介紹5種不同的方式，利用Java類來實例化Java對象。

1. 使用new關鍵字

? 采用new關鍵字實例化對象是Java中最為常見的方法，下面是采用new關鍵字實例化對象的示例。在開始之前，我們先準備好一個Java類：Student.java。

package com.ramostear.oops;public class Student{ private String name; private String nickname; public Student(String name,String nickname){ this.name = name; this.nickname = nickname; } public String getName(){ return name; } public void setName(String name){ this.name = name; } public String getNickname(){ return nickname; } public void setNickname(String nickname){ this.nickname = nickname; }}

接下來，我們通過new關鍵字來創建幾個學生：

package com.ramostear.oops;public class TestNewStudent{ public static void main(String[] args){ Student zhangsan = new Student("Zhangsan","張三"); Student lisi = new Student(); lisi.setName("Lisi"); lisi.setNickname("李四")； }}

2. 使用Class類的newInstance()方法

? 首先，我們可以通過Class.forName()方法動態加載目標類，然后再調用newInstance()方法，動態實例化對象。同理，在開始之前，我們需要準備一個目標類：Student.java。

package com.ramostear.oops;public class Student{ private String name = "Zhangsan"; private String nickname = "張三"; public Student(){ super(); } public Student(String name,String nickname){ super(); this.name = name; this.nickname = nickname; } public String getName(){ return name; } public void setName(String name){ this.name = name; } public String getNickname(){ return nickname; } public void setNickname(String nickname){ this.nickname = nickname; }}

接下來，將演示如何通過newInstance()方法來創建新的對象：

package com.ramostear.oops;public class TestUseNewInstanceMethod{ public static void main(String[] args){ try{ String className = "com.ramostear.oops.Student"; Class clz = Class.forName(className); Student student = (Student) clz.newInstance(); System.out.println("student name :"+ student.getName()+", nickname: "+student.getNickname()); }catch(InstantiationException | IllegalAccessException | ClassNotFoundException e){ e.printStackTrace(); } }}

運行main()方法，將輸出如下信息：

student name :Zhangsan, nickname:張三

3. 使用Constructor.newInstance()方法

? 與Class類的newInstance()方法相似，我們還可以使用java.lang.reflect.Constructor類的newInstance()方法來創建新的對象。同樣，我們先準備一個目標類：

package com.ramostear.oops;public class Student{ private String name = "Constructor"; private String nickname = "構造器"; public Student(){ super(); } public Student(String name,String nickname){ super(); this.name = name; this.nickname = nickname; } public String getName(){ return name; } public void setName(String name){ this.name = name; } public String getNickname(){ return nickname; } public void setNickname(String nickname){ this.nickname = nickname; }}

接下來，我們看看如何使用Constructor的newInstance()方法創建新的對象：

package com.ramostear.oops;import java.lang.reflect.Constructor;import java.lang.reflect.InvocationTargetException;public class UseConstructorNewInstanceMethod{ public static void main(String[] args){ Constructor studentConstructor; try{ studentConstructor = Student.class.getConstructor(); Student student = studentConstructor.newInstance(); System.out.println("student name :"+ student.getName()+", nickname: "+student.getNickname()); }catch(InstantiationException | IllegalAccessException | IllegalArgumentException | InvocationTargetException | NoSuchMethodException | SecurityException e){ e.printStackTrace(); } } }

執行main()方法，將在控制臺輸出如下信息：

student name:Constructor, nickname:構造器

4. 使用反序列化

? 如果要使用反序列化創建對象，則目標類首先要實現Serializable接口。Serializable是一個標記接口。在本次示例中，我們先創建一個Student對象，并將其保存到data.txt文件中，然后在通過反序列化操作，讀取data.txt中的數據，并創建新的對象。

package com.ramostear.oops;import java.io.Serializable;public class Student implements Serializable{ private String name; private String nickname; public Student() { super(); } public Student(String name, String nickname) { super(); this.name = name; this.nickname = nickname; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getNickname() { return nickname; } public void setNickname(String nickname) { this.nickname = nickname; }}

接下來，將通過一個簡單的示例，演示如何使用反序列化的方式創建新的對象：

package com.ramostear.oops;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;public class StudentDemo { public static void main(String[] args) { String filePath = "data.txt"; Student student1 = new Student("Deserialization", "反序列化"); try { FileOutputStream fileOutputStream = new FileOutputStream(filePath); ObjectOutputStream outputStream = new ObjectOutputStream(fileOutputStream); outputStream.writeObject(student1); outputStream.flush(); outputStream.close(); FileInputStream fileInputStream = new FileInputStream(filePath); ObjectInputStream inputStream = new ObjectInputStream(fileInputStream); Student student2 = (Student) inputStream.readObject(); inputStream.close(); System.out.println("Student name:"+student2.getName()+", nickname:"+student2.getNickname()); } catch (Exception ee) { ee.printStackTrace(); } }}

執行上述代碼，將在控制臺輸出如下信息：

Student name:Deserialization,nickname:反序列化

5. 使用對象克隆創建新的對象

? clone()方法可以創建現有對象的副本，但在使用clone()方法前，需保證模板類實現了Cloneable接口，Cloneable接口也是一個標記類接口。下面是使用克隆方式創建新對象的完整示例：

package net.javaguides.corejava.oops;import java.io.Serializable;public class Student implements Cloneable { private String name; private String nickname; public Student() { super(); } public Student(String name, String nickname) { super(); this.name = name; this.nickname = nickname; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getNickname() { return nickname; } public void setNickname(String nickname) { this.nickname = nickname; } public static void main(String args[]) { Student stu1 = new Student("Clone", "克隆"); try { Student stu2 = (Student) stu1.clone(); System.out.println("Student name :"+stu2.getName()+",nickname:"+stu2.getNickanme()); } catch (CloneNotSupportedException e) { e.printStackTrace(); } }}

運行上述代碼，控制臺將輸出如下信息：

Student name： Clone,nickname:克隆

總結

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