这里有新鲜出炉的Java并发编程示例,程序狗速度看过来!
java 是一种可以撰写跨平台应用软件的面向对象的程序设计语言,是由Sun Microsystems公司于1995年5月推出的Java程序设计语言和Java平台(即JavaEE(j2ee), JavaME(j2me), JavaSE(j2se))的总称。
本篇文章是关于java 如何自己创建自定义数组,这里给大家一个小实例,希望能帮助有所需要的同学
1.java创建自定义类数组方法:
- Student []stu = new Student[3];
- for(int i = 0; i < 3; i ++)
- {
- stu[i] = new Student();
- }
2.否则会提示空指针异常
- package project;
- import java.io.*;
- import java.util.Scanner;
- class Student
- {
- private int id;
- private String name;
- private int score;
- 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 score)
- {
- this.score = score;
- }
- public int getScore()
- {
- return this.score;
- }
- }
- public class project2 {
- File file = new File("E:/data.txt");
- FileWriter filewrite = null;
- BufferedWriter write = null;
- FileReader fileread = null;
- BufferedReader read = null;
- Student []stu = new Student[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:");
- Scanner in = new Scanner(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.
来源: http://www.phperz.com/article/17/1117/360443.html