1、将字符串「a-b-c-d-e-f」按 「-」 切割,找到 「c」字符,替换为大写,然后倒序输出 「f-e-d-C-b-a」。
public class Test1 { public static void main(String[] args) { String s1 = "a-b-c-d-e-f"; String[] s2 = s1.split("-"); for(String s3:s2) { System.out.println(s3); } String s4 = ""; for(int i = 0;i<s2.length;i++) { s4 += s2[i] +"-"; } String s5 = s4.substring(0,s4.length()-1); s5 = s5.replace("c", "C"); System.out.println(new StringBuffer(s5).reverse().toString()); } }
2、定义学生类(包含学号、姓名、年龄),将你所在小组组员添加到一个集合中,并按学号排序后输出。
public class Student implements Comparable<Student>{ private int code; private String name; private int age; public int getCode() { return code; } public void setCode(int code) { this.code = code; } 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 Student(int code, String name, int age) { super(); this.code = code; this.name = name; this.age = age; } @Override public int compareTo(Student o) { int flag; if (this.code > o.code) { flag = -1; } else if (this.code == o.code) { flag = 0; } else { flag = 1; } return flag; } @Override public String toString() { return "Student [code=" + code + ", name=" + name + ", age=" + age + "]"; } }
import java.util.ArrayList; import java.util.Collections; import java.util.List; public class Test2 { public static void main(String[] args) { List<Student> teams = new ArrayList<Student>(); // 新建学生对象 Student stu1 = new Student(1, "陆洋", 24); Student stu2 = new Student(3, "顾锐", 19); Student stu3 = new Student(2, "关凌", 24); Student stu4 = new Student(4, "钱佳雷", 25); // 向集合添加学生对象 teams.add(stu1); teams.add(stu2); teams.add(stu3); teams.add(stu4); // 按学号倒叙排列 Collections.sort(teams); // 遍历学生 for (Student stu : teams) { System.out.println(stu); } } }3、紧接第二题,用单例设计一个服务类,并定义一个方法,可以随机抽取集合中的某个学生对象,并打印输出。
import java.util.List; public class Service { private static Service service = new Service(); private Service() { } public static Service getInstance() { return service; } public Student randomStu(List<Student> stus) { if (null != stus && !stus.isEmpty()) { return stus.get((int)(Math.random() * stus.size())); } else { return null; } } }
import java.util.ArrayList; import java.util.List; public class Test3 { public static void main(String[] args) { List<Student> teams = new ArrayList<Student>(); Student stu1 = new Student(1, "陆洋", 24); Student stu2 = new Student(3, "顾锐", 19); Student stu3 = new Student(2, "关凌", 24); Student stu4 = new Student(4, "钱佳雷", 25); teams.add(stu1); teams.add(stu2); teams.add(stu3); teams.add(stu4); // 通过静态方法获取对象 Service service = Service.getInstance(); System.out.println("==========随机抽取学生============="); Student randomStu = service.randomStu(teams); System.out.println(randomStu); } }