Java 创建对象的四种方式

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Java 创建对象的四种方式

1、使用new关键值创建对象

User user = new user();
user.setName("小明");
user.setPass("123456");
System.out.println(user );

2、使用clone

User user= new User ();
Object clone = user.clone();
System.out.println(clone);

详细的clone （可以克隆之前的对象，之前对象需要实现接口Cloneable）

public class CloneTest {

public static void main(String[] args) {
try {
cloneTest();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
}
static void cloneTest() throws CloneNotSupportedException {
User user = new User();
user.setPassWord("123456789");
user.setUserName("小明");
User cloneUser = (User) user.clone();
cloneUser.setYearold(18);
System.out.println(cloneUser.toString());

}

}
class User implements Cloneable{
private String userName;
private String passWord;
private Integer yearold;
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassWord() {
return passWord;
}
public void setPassWord(String passWord) {
this.passWord = passWord;
}
public Integer getYearold() {
return yearold;
}
public void setYearold(Integer yearold) {
this.yearold = yearold;
}
@Override
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
@Override
public String toString() {
return "User [userName=" + userName + ", passWord=" + passWord + ", yearold=" + yearold + "]";
}
}

运行结果

User [userName=小明, passWord=123456789, yearold=18]

3、使用反射

Class c = Class.forName("com.xxx.User");
Object o = c.newInstance();
System.out.println(o);

4、反序列化

// 先序列化
User user= new User();
ObjectOutputStream os = new ObjectOutputStream(new FileOutputStream("user.obj"));
os.writeObject(user);
// 再反序列化
ObjectInputStream is = new ObjectInputStream(new FileInputStream("user.obj"));
Object o = is.readObject();
System.out.println(o);

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