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 |
