Java中创建对象的四种方式

Java中创建对象的四种方式

(1) 用new语句创建对象，这是最常见的创建对象的方法。

(2) 运用反射手段,调用java.lang.Class或者java.lang.reflect.Constructor类的newInstance()实例方法。

(3) 调用对象的clone()方法。

(4) 运用反序列化手段，调用java.io.ObjectInputStream对象的 readObject()方法。

一.用new语句创建对象

Java代码





User user = new User()

二.运用反射手段

(1)调用java.lang.Class.newInstance()

Java代码





Class.forName(classname).newInstance()

Wife wife = (Wife) Class.forName("com.java.clone.Wife").newInstance();

(2)调用java.lang.reflect.Constructor类的newInstance()

Java代码





Constructor<Wife> constructor = Wife.class.getDeclaredConstructor(int.class,String.class);

Wife wife = (Wife) constructor.newInstance(1,"nihao");

三.调用对象的clone()方法

详情参考：
/article/3968175.html

Java代码





Wife wife = new Wife(1,"wang");

Wife wife2 = null;

wife2 = (Wife) wife.clone();//运用clone()方法产生新对象

四.运用反序列化手段

被序列化的对象必须implements Serializable

Java代码





public class BeanUtil {

@SuppressWarnings("unchecked")

public static <T> T cloneTo(T src) throws RuntimeException {

ByteArrayOutputStream memoryBuffer = new ByteArrayOutputStream();

ObjectOutputStream out = null;

ObjectInputStream in = null;

T dist = null;

try {

out = new ObjectOutputStream(memoryBuffer);

out.writeObject(src);

out.flush();

in = new ObjectInputStream(new ByteArrayInputStream(

memoryBuffer.toByteArray()));

dist = (T) in.readObject();

} catch (Exception e) {

throw new RuntimeException(e);

} finally {

if (out != null)

try {

out.close();

out = null;

} catch (IOException e) {

throw new RuntimeException(e);

}

if (in != null)

try {

in.close();

in = null;

} catch (IOException e) {

throw new RuntimeException(e);

}

}

return dist;

}

public static void main(String[] args){

Husband husband = new Husband(1);

Wife wife = new Wife(1,"jin");

husband.setWife(wife);

Husband husband2 = cloneTo(husband);//运用反序列生成了一个对象

}

}