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Get a tutorial on constructor examples in classes

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Release: 2017-06-28 09:36:40
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Get all public constructors of the class through the class.getConstructors() method.

If the class has no public constructor, or the class is an array class, or the class reflects a primitive type or void, then an array of length 0 is returned.

 1 import lombok.Data; 2  3 /** 4  * Created by hunt on 2017/6/27. 5  * 测试的实体类 6  * @Data 编译后会自动生成set、get、无惨构造、equals、canEqual、hashCode、toString方法 7  */ 8 @Data 9 public class Person {10     private String name;11     private int age;12     public Person(){}13     public Person(String name){...}14     protected Person(int age){...}15     private Person(String name,int age){...}16 17 }
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 1 /** 2  * Created by hunt on 2017/6/27. 3  */ 4 public class NewInstanceTest { 5     public static void main(String[] args) { 6         Class<Person> personClass = Person.class;//获取Class实例 7         Constructor<?> constructor[] = personClass.getConstructors(); 8         for (Constructor<?> con : constructor) { 9             System.out.println(con);10         }11 12     }13 }
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 1 import lombok.Data; 2  3 /** 4  * Created by hunt on 2017/6/27. 5  * 测试的实体类 6  * @Data 编译后会自动生成set、get、无惨构造、equals、canEqual、hashCode、toString方法 7  */ 8 @Data 9 public class Person {10     private String name;11     private int age;12     private Person(String name){...}13     protected Person(int age){...}14     private Person(String name,int age){...}15 16 }
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 1 import java.lang.reflect.Constructor; 2  3 /** 4  * Created by hunt on 2017/6/27. 5  */ 6 public class NewInstanceTest { 7     public static void main(String[] args) { 8         Class<Person> personClass = Person.class;//获取Class实例 9         Constructor<?> constructor[] = personClass.getConstructors();10         System.out.println(constructor.length);11         for (Constructor<?> con : constructor) {12             System.out.println(con);13         }14 15     }16 }
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Get all the constructors of the class (public, protected, default, and private constructors) through the class.getDeclaredConstructors() method.

If the class has a default constructor, it is included in the returned array. If this Class object represents an interface, a primitive type, an array class, or void, this method returns an array of length 0.

 1 /** 2  * Created by hunt on 2017/6/27. 3  */ 4 public class NewInstanceTest { 5     public static void main(String[] args) { 6         Class<Person> personClass = Person.class;//获取Class实例 7         Constructor<?> constructor[] = personClass.getDeclaredConstructors(); 8         System.out.println(constructor.length); 9         for (Constructor<?> con : constructor) {10             System.out.println(con);11         }12 13     }14 }
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Note: The elements in the returned method array are not sorted, nor in any specific order.

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