1.直接new (无需多言)
2.使用反射机制创建
/**
*
* @author eastw
*
* 待创建的类
*/
public class Hello {
public void sayWorld() {
System.out.println("Hello world!");
}
}
/**
*
* @author eastw
*
* 使用反射的机制创建对象 Class类的newInstance方法
*/
public class Two {
public static void main(String[] args)
throws ClassNotFoundException, InstantiationException, IllegalAccessException {
// 获取类对象
Class<?> helloClass = Class.forName("com.eastw.mode.Hello");
// newInstance创建对象
Hello hello = (Hello) helloClass.newInstance();
hello.sayWorld();
}
}
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
/**
*
* @author eastw
*
* 使用Constructor类的newInstance方法
*/
public class Three {
public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, SecurityException,
InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
// 获取类对象
Class<?> helloClass = Class.forName("com.eastw.mode.Hello");
// 获取构造器
Constructor<?> constructor = helloClass.getConstructor();
// 使用newInstance
Hello hello = (Hello) constructor.newInstance();
hello.sayWorld();
}
}
3.使用clone 生成新的对象
/**
*
* @author eastw
*
* 待创建的类
*/
public class HelloClone implements Cloneable {
public void sayWorld() {
System.out.println("Hello world!");
}
/**
* 把这个方法重写一下就行，什么都不写
*/
@Override
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
/**
*
* @author eastw
*
* 采用clone clone时，需要已经有一个分配了内存的源对象，创建新对象时，首先应该分配一个和源对象一样大的内存空间。
*
* 要调用clone方法需要实现Cloneable接口，由于clone方法是protected的，所以修改Hello类。
*/
public class Four {
public static void main(String[] args) {
HelloClone hello1 = new HelloClone();
try {
HelloClone h2 = (HelloClone) hello1.clone();
h2.sayWorld();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
}
}
4.采用序列化机制
import java.io.Serializable;
/**
*
* @author eastw
*
* 待创建的类
*/
public class HelloSerializable implements Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
public void sayWorld() {
System.out.println("Hello world!");
}
}
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
/**
*
* @author eastw
*
* 采用序列化机制
*/
public class Five {
private static ObjectOutputStream oos;
private static ObjectInputStream ois;
public static void main(String[] args) {
HelloSerializable hello = new HelloSerializable();
// 准备一个文件用于存储该对象的信息
File file = new File("hello.obj");
try {
FileOutputStream fos = new FileOutputStream(file);
oos = new ObjectOutputStream(fos);
FileInputStream fis = new FileInputStream(file);
ois = new ObjectInputStream(fis);
// 序列化对象，写入到磁盘中
oos.writeObject(hello);
// 反序列化对象
HelloSerializable newHello = (HelloSerializable) ois.readObject();
// 测试方法
newHello.sayWorld();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
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