Java Exception Handling Mechanism (2)

Java Exception Handling Mechanism (2)

1. Role of throw

Class Usre {

Private int age;

Public void setAge (int age ){

If (age <0 ){

RuntimeException e = new RuntimeException ("Age cannot be negative"); // generate an exception object

Throw e; // throw

}

This. age = age;

}

}

Class Test {

Public static void main (String args []) {

User user = new User ();

User. setAge (-20 );

}

}

Throw is used to throw an exception object.

2. Role of throws

Class Usre {

Private int age;

Public void setAge (int age) throws Exception {

If (age <0 ){

Exception e = new Exception ("Age cannot be negative"); // generate an Exception object

Throw e; // throw

}

This. age = age;

}

}

Class Test {

Public static void main (String args []) {

User user = new User ();

Try {

User. setAge (-20 );

}

Catch {

System. out. println (e );

}

}

}

Throws: When an exception may occur in a function, you can use try... catch can handle code that may generate exceptions. It can also be declared after the function to generate an Exception (declaration method: add the possible Exception type after throws). Once declared, therefore, this function has no responsibility to handle this exception, but to handle this exception from the called place.