How to access member variables in java

Through the getField() method of the Class object, you can obtain all or specified member variables Field included in this class. Field provides the following two methods to read and set member variable values.

1. getxx(Objectobj):

Get the member variable value of the obj object. The xxx here corresponds to the basic type in 8. If the type of the member variable If it is a reference type, cancel the xxx

2 and setxx(Objectobj, xxxval) after get:

Set the member variable value of the obj object to the val value. The xxx here corresponds to 8 basic types. If the member type is a reference type, cancel the xxx

3 and instance

 Person person = new Person();
 // 获取name成员变量Field
 Field nameField = person.getClass().getDeclaredField("name");
 // 启用访问控制权限
 nameField.setAccessible(true);
 // 获取person对象的成员变量name的值
 String name = (String) nameField.get(person);
 System.out.println("name = " + name);
 // 设置person对象的成员变量name的值
 nameField.set(person, "lisi");
 System.out.println(person);

What collection classes are there in Java?

Collections in Java are mainly divided into four categories:

1. List: ordered, repeatable;

2. Queue: ordered, repeatable Duplicate;

3. Set collection: non-repeatable;

4. Map: unordered, with unique keys and non-unique values.

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