Custom exception class myexception

1. according to Exception Redefine the exception class

package java2;

public class MyException extends Exception{
    
//  The unique identifier of the class 
	static final long serialVersionUID = -338751699244229948L;
	public MyException(){
    
//  Constructors 1
	}
	public MyException(String msg){
    
//  Constructors 2
		super(msg);
	}
}

2. Use custom exception classes MyException Throw an exception

class Student {
    
	private int id;
// 2.throws: Automatically catch thrown exceptions 
	public void regist(int id) throws MyException{
    
		if(id>0){
    
			this.id=id;
		}else{
    
// 1.throw: Throw an exception manually 
			throw new MyException(" The data you entered is negative ！");
		}
	}
}

3. try-catch Get exception class data

@Test
	public void testStudent(){
    
		Student s=new Student();
// 3.try-catch The location of the calling method catches an exception 
		try {
    
			s.regist(-1114);
		} catch (Exception e) {
    
// 4.getMessage Get unexpected string 
			System.out.println(e.getMessage());
			e.printStackTrace();
		}
	}