我们在写Java的程序的过程中总是会看到static，但是你知道他的性质和用法及其原因吗

java">package com.java.picture;public class StudentB {private String name;private int age;private String gender;public StudentB() {}public StudentB(String name, int age, String gender) {this.name = name;this.age = age;this.gender = gender;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String getGender() {return gender;}public void setGender(String gender) {this.gender = gender;}
}

java">package com.java.picture;import java.util.ArrayList;public class StudentUntil {public static int studentMax(ArrayList<StudentB> list) {int max = 0;for (int i = 0; i < list.size(); i++) {int age = list.get(i).getAge();if(age > max){max = age;}}return max;}
}

java">package com.java.picture;import java.util.ArrayList;public class Test02 {public static void main(String[] args) {//创建一个集合来存储3个学生信息ArrayList<StudentB> list = new ArrayList<>();StudentB student1 = new StudentB("zhangsan",16,"man");StudentB student2 = new StudentB("lisi",17,"woman");StudentB student3 = new StudentB("wangwu",18,"man");//把学生信息加到我们的集合中list.add(student1);list.add(student2);list.add(student3);int Max  = StudentUntil.studentMax(list);System.out.println(Max);}
}