7017-5-19实训的第五天

1.定义：ArrayList是一个动态数组，该数组的容量能任意变化（增大或减少）。
2.使用方法：ArrayList <类名1> 数组名=new ArrayList<类名2>();
（注意：类名1和类名2是相同的，类名2可以省略）
3.int类型就用integer
导包的快捷键：ctrl shift o
4.例子：

例子1package T1;import java.util.ArrayList;public class demo {public static void main(String[] args) {// TODO Auto-generated method stubArrayList<String> str = new ArrayList<String>();str.add("hey");str.add("hello");str.add("hi");System.out.println(str);for (int i = 0; i < str.size(); i++) {// String s = str.get(i);System.out.print(str.get(i) + " ");}}}

例子2//创建一个类package P02;public class Student {String name;String gender;int age;String classname;Student() {// TODO Auto-generated constructor stub}/** *  * @param name * @param gender * @param age * @param classname */public Student(String name, String gender, int age, String classname) {this.name = name;this.gender = gender;this.age = age;this.classname = classname;}}//利用创建好的类创建数组package P02;import java.util.ArrayList;public class Text {public static void main(String[] args) {// TODO Auto-generated method stubArrayList<Student> students = new ArrayList<Student>();Student t1 = new Student("jack", "男", 22, "2班");Student t2 = new Student("frank", "男", 23, "3班");Student t3 = new Student("marry", "女", 24, "4班");students.add(t1);students.add(t2);students.add(t3);for (int i = 0; i < students.size(); i++) {Student s = students.get(i);System.out.println("学生姓名："+s.name+" 学生性别："+s.gender+" 学生年龄："+s.age+" 学生班级："+s.classname);}/*for (Student stu : students) {System.out.println(stu.classname+"--"+stu.gender);}*/}}