1. 자바 ：
학생 [] stu = 신입생 [3]; for (int i = 0; i <3; i ++) {stu [i] = new Student ();2. 否则会提示空指针异常
패키지 프로젝트; import java.io.*; import java.util.scanner; 클래스 학생 {private int id; 개인 문자열 이름; 개인 INT 점수; public void setid (int id) {this.id = id; } public int getId () {return this.Id; } public void setName (문자열 이름) {this.name = 이름; } public String getName () {return this.name; } public void setScore (int score) {this.score = score; } public int getscore () {return this.score; }} public class project2 {file file = 새 파일 ( "e : /data.txt"); filewriter filewrite = null; 버퍼링 라이터 쓰기 = null; filereader fileread = null; BufferedReader read = null; 학생 [] STU = 신입생 [3]; public void put () {try {filewrite = new filewriter (파일); } 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 :"); SCANNER IN = NEW SCANNER (System.In); try {string str = in.nextline (); 문자열 데이터 [] = 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; 이중 Ave; try {fileread = new Filereader (파일); } 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 (예외 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); {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.