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This article mainly shows you "JAVA how to achieve random roll call", the content is easy to understand, clear, hope to help you solve your doubts, the following let the editor lead you to study and learn "JAVA how to achieve random roll call" this article.

Special note: you can not directly output the collection or array objects, that is the address of the output, always output to the variables inside.

/ *

Random roll call, set improvement (student's name and age)

In reality, there are things like students, which use the form of defining classes to describe students' things.

Attribute: name, age

The name is stored in an array and the container is replaced with a collection

String [] s = {","}

Is the name of the student stored in the collection? The Student type should be stored

Storage students:

Student type, stored in collection

Overview: traversing collections

Random: random number, as an index, to find elements in the collection

Three functions, shared data, collection container

Define three methods that must pass a set of parameters

, /

Import java.util.ArrayList

Import java.util.Random

Public class CallName {

Public static void main (String [] args) {

/ / defines a collection that stores StudentName type variables

ArrayList array = new ArrayList ()

/ / call the add method

Add (array)

/ / call to traverse the collection

PrintArrayList (array)

RandomStudentName (array)

}

/ *

Random number, as the index of the collection, to find the element in the collection

, /

Public static void randomStudentName (ArrayList array) {

Random r = new Random ()

Int number = r.nextInt (array.size ())

/ / Random number, index, get to the collection

StudentName s = array.get (number)

System.out.println (s.name + "" + s.age)

}

/ *

An overview of students' information, traversing collections

, /

Public static void printArrayList (ArrayList array) {

For (int I = 0; I < array.size (); iTunes +) {

/ / when storing a collection, the collection .add (sn1) sn1 is a variable of type StudentName

/ / when getting, collect the .get method to get what is obtained, or a variable of type StudentName

StudentName s = array.get (I)

System.out.println (s.name + "" + s.age)

}

}

/ *

Define a method to store the name and age of the student

Create a variable of type StudentName and store it in the collection

, /

Public static void add (ArrayList array) {

/ / create a StudentName type variable

StudentName sn1 = new StudentName ()

StudentName sn2 = new StudentName ()

StudentName sn3 = new StudentName ()

StudentName sn4 = new StudentName ()

StudentName sn5 = new StudentName ()

Sn1.name = "Zhang San 1"

Sn1.age = 201

Sn2.name = "Zhang San2"

Sn2.age = 202

Sn3.name = "Zhang San3"

Sn3.age = 203

Sn4.name = "Zhang San4"

Sn4.age = 204

Sn5.name = "Zhang San5"

Sn5.age = 205

/ / store the StudentName variable in the collection

Array.add (sn1)

Array.add (sn2)

Array.add (sn3)

Array.add (sn4)

Array.add (sn5)

}

}

/ *

A class that describes students' things.

Attribute: name and age

Variables of student type, stored in the collection

, /

Public class StudentName {

String name

Int age

}

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