标题: Java中创建对象的5种方式（2） [打印本页]

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作者: look_w    时间: 2018-12-15 14:20     标题: Java中创建对象的5种方式（2）

例子让我们看一看为下面这个Employee类创建对象：


class Employee implements Cloneable, Serializable {    private static final long serialVersionUID = 1L;    private String name;    public Employee() {        System.out.println("Employee Constructor Called...");    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    @Override    public int hashCode() {        final int prime = 31;        int result = 1;        result = prime * result + ((name == null) ? 0 : name.hashCode());        return result;    }    @Override    public boolean equals(Object obj) {        if (this == obj)            return true;        if (obj == null)            return false;        if (getClass() != obj.getClass())            return false;        Employee other = (Employee) obj;        if (name == null) {            if (other.name != null)                return false;        } else if (!name.equals(other.name))            return false;        return true;    }    @Override    public String toString() {        return "Employee [name=" + name + "]";    }    @Override    public Object clone() {        Object obj = null;        try {            obj = super.clone();        } catch (CloneNotSupportedException e) {            e.printStackTrace();        }        return obj;    }}[url=][/url]


下面的Java程序中，我们将用5种方式创建Employee对象。你可以从GitHub找到这些代码。
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public class ObjectCreation {    public static void main(String... args) throws Exception {        // By using new keyword        Employee emp1 = new Employee();        emp1.setName("Naresh");        System.out.println(emp1 + ", hashcode : " + emp1.hashCode());        // By using Class class's newInstance() method        Employee emp2 = (Employee) Class.forName("org.programming.mitra.exercises.Employee")                               .newInstance();        // Or we can simply do this        // Employee emp2 = Employee.class.newInstance();        emp2.setName("Rishi");        System.out.println(emp2 + ", hashcode : " + emp2.hashCode());        // By using Constructor class's newInstance() method        Constructor<Employee> constructor = Employee.class.getConstructor();        Employee emp3 = constructor.newInstance();        emp3.setName("Yogesh");        System.out.println(emp3 + ", hashcode : " + emp3.hashCode());        // By using clone() method        Employee emp4 = (Employee) emp3.clone();        emp4.setName("Atul");        System.out.println(emp4 + ", hashcode : " + emp4.hashCode());        // By using Deserialization        // Serialization        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("data.obj"));        out.writeObject(emp4);        out.close();        //Deserialization        ObjectInputStream in = new ObjectInputStream(new FileInputStream("data.obj"));        Employee emp5 = (Employee) in.readObject();        in.close();        emp5.setName("Akash");        System.out.println(emp5 + ", hashcode : " + emp5.hashCode());    }}



程序会输出：
Employee Constructor Called...Employee [name=Naresh], hashcode : -1968815046Employee Constructor Called...Employee [name=Rishi], hashcode : 78970652Employee Constructor Called...Employee [name=Yogesh], hashcode : -1641292792Employee [name=Atul], hashcode : 2051657Employee [name=Akash], hashcode : 63313419

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