1. Java 创建自定义类数组方法 ：
Студент [] stu = новый студент [3]; for (int i = 0; i <3; i ++) {stu [i] = new Student ();｝2. 否则会提示空指针异常
пакетный проект; Импорт java.io.*; import java.util.scanner; Class Student {Private Int ID; Приватное название строки; частный балл; public void setId (int id) {this.id = id; } public int getId () {return this.id; } public void setName (string name) {this.name = name; } public String getName () {return this.name; } public void setScore (int chold) {this.score = comp; } public int getScore () {return this.score; }} открытый класс Project2 {file file = new File ("e: /data.txt"); Файлверритер файл whrite = null; BufferedWriter write = null; FileReader fileread = null; BufferedReader Read = null; Студент [] stu = новый студент [3]; public void put () {try {fileWrite = new FileWriter (file); } catch (ioException e) {// todo 自动生成的 catch 块 e.printstacktrace (); } write = new BufferedWriter (fileWrite); for (int i = 0; i <3; i ++) {System.out.println ("请输入第" + (i + 1) + "个学生的 id, 姓名, 成绩:"); Сканер в = новый сканер (System.in); try {string str = in.nextline (); String Data [] = str.split ("" "); for (int j = 0; j <3; j ++) {write.write (data [j]); write.newline (); }} catch (ioException e) {// todo 自动生成的 catch 块 e.printstacktrace (); }} try {write.close (); filewrite.close (); } catch (ioException e) {// todo 自动生成的 catch 块 e.printstacktrace (); }} public void get () {int sum = 0; Double Ave; try {fileread = new FileReader (file); } catch (filenotfoundexception e) {// todo 自动生成的 Catch 块 e.printstackTrace (); } read = new BufferedReader (FileRead); for (int i = 0; i <3; i ++) {stu [i] = new Student (); try {stu [i] .setid (integer.parseint (read.readline ())); stu [i] .setname (read.readline ()); stu [i] .setscore (integer.parseint (read.readline ())); } catch (Exception e) {// todo 自动生成的 Catch 块 e.printstackTrace (); }} for (int i = 0; i <3; i ++) {sum += stu [i] .getScore (); } ave = sum * 1,0/3; System.out.println ("学生的平均成绩为 ：" + Ave); try {read.close (); fileread.close (); } catch (ioException e) {// todo 自动生成的 catch 块 e.printstacktrace (); }} public static void main (string [] args) {project2 pro = new Project2 (); pro.put (); pro.get (); }}总结 ：
这样我们就可以在项目当中, 根据项目需求自己来定义想要的数组.