学习打卡第一天
1 package Exception; 2 3 public class Student { 4 private void speak(int m)throws MyException 5 { 6 if(m>1000) 7 { 8 throw new MyException("该数大于1000"); 9 } 10 } 11 12 13 public static void main(String[] args) { 14 Student student = new Student(); 15 try 16 { 17 student.speak(1010); 18 }catch(MyException e) 19 { 20 System.out.println(e.getMessage()); 21 } 22 23 } 24 25 } 26 class MyException extends Exception 27 { 28 String message; 29 public MyException(String ErrorMessage) 30 { 31 message = ErrorMessage; 32 } 33 public String getMessage() 34 { 35 return message; 36 } 37 }
以上是今日学习的异常处理以及捕捉,在编程中需要去考虑你写的程序会出现的情况,并且去处理它,保证不让你的程序崩溃。
1 package list; 2 import java.util.*; 3 public class ListTest { 4 LinkedList<Integer>list = new LinkedList<Integer>();//ArrayList与LinkedList的区别在于ArrayList插入对象和删除对象时比LinkedList慢 5 public void add(int n) 6 { 7 list.add(n); 8 } 9 public void remove(int index) 10 { 11 list.remove(index); 12 } 13 public int getSize() 14 { 15 return list.size(); 16 } 17 public int get(int index) 18 { 19 return list.get(index); 20 } 21 public static void main(String[] args) { 22 ListTest list = new ListTest(); 23 for(int i =1;i<=100;i++) 24 { 25 list.add(i); 26 } 27 list.remove(10); 28 for(int i =0;i<list.getSize();i++) 29 { 30 System.out.print(list.get(i)+" "); 31 if(i%10 == 0 && i != 0) 32 { 33 System.out.println(); 34 } 35 } 36 } 37 38 }
1 package set; 2 3 public class Student implements Comparable<Object>{ 4 5 int id; 6 String name; 7 char sex; 8 public Student(int id,String name,char sex) 9 { 10 this.id = id; 11 this.name = name; 12 this.sex = sex; 13 } 14 public void print() 15 { 16 System.out.println("学号:"+this.id); 17 System.out.println("姓名:"+this.name); 18 System.out.println("性别:"+this.sex); 19 } 20 public int compareTo(Object o) 21 { 22 Student s = (Student)o; 23 int result = this.id>s.id ? 1 : (this.id == s.id ? 0 : -1); 24 return result; 25 } 26 }
package set; import java.util.Iterator; import java.util.TreeSet; public class SetTest { TreeSet<Student> set = new TreeSet<Student>();//TreeSet和TreeMap 会自动排序 需要去实现comparaTo函数 public void add(Student s) { set.add(s); } public void remove(Student s) { set.remove(s); } public void allShow() { Iterator it = set.iterator(); while(it.hasNext()) { Student s = (Student)it.next(); s.print(); } } public static void main(String[] args) { SetTest set = new SetTest(); Student s1 = new Student(125,"李丽",'女'); Student s2 = new Student(215,"李伟",'男'); Student s3 = new Student(145,"李春江",'男'); set.add(s1); set.add(s2); set.add(s3); set.allShow(); } }
以上是今日学习的集合类,基本类型存放可以存放在数组中,对象一般存放在集合中,集合中可以自动增长长度,以上Student类和SetTest类在同一packge下没有写在同一个java文件下,知道了TreeMap和TreeSet会进行自动排序,但是需要自己去实现那个comparaTo函数,不然会报错,以上就是今日所学习。