IllegalArgumentException返回对象清除中给定的值

Question

the bellow code is part of a program that is suppose to throw an IllegalArgumentException if the given value is out of range. But instead, if the given numbers in setTime() is out of range, it would return the corresponding value when the object was created in the main method instead of the desired error message! what is the reason

here is the code:

public class MyTime {

    private int hour = 0;
    private int minute = 0;
    private int second = 0;

    public static void main (String [] args) {
// when the value is out of range in setTime(), the value given bellow in t1 is returned
        MyTime t1 = new MyTime (10,10,10);
        t1.setTime(26, 23, 14);
        System.out.println("toString(): " + t1);   
    }

    public MyTime (int hour, int minute, int second) {
        this.hour = hour;
        this.minute = minute;
        this.second = second;
    }
    public void setTime (int hour, int minute, int second) {
        try {
            if (hour > 0 && hour < 23 ) {
                this.hour = hour;
            }

            if (minute > 0 && minute < 59 ) {
                this.minute = minute;
            }

            if (second > 0 && second < 59 ) {
                this.second = second;
            }            

        }
        catch (IllegalArgumentException exception) {
            System.out.println("Invalid entry");
        }
    }  

Answer 1

You said it should throw the exception. So you shouldn't catch it inside the method. Remove the try{...}catch{..} around the if 's

public void setTime (int hour, int minute, int second) {

    if (hour > 0 && hour < 23 ) {
        this.hour = hour;
    } else {
        throw new IllegalArgumentException();
    }

    if (minute > 0 && minute < 59 ) {
        this.minute = minute;
    } else {
        throw new IllegalArgumentException();
    }

    if (second > 0 && second < 59 ) {
        this.second = second;
    } else {
        throw new IllegalArgumentException();
    }       

}

Answer 2

You have to throw the exception.

public void setTime (int hour, int minute, int second) {
    try {
        if (hour > 0 && hour < 23 ) {
            this.hour = hour;
        }else{
            throw new IllegalArgumentException("Invalid Hour Value");
        }

        if (minute > 0 && minute < 59 ) {
            this.minute = minute;
        }else{
            throw new IllegalArgumentException("Invalid Minutes Value");
        }

        if (second > 0 && second < 59 ) {
            this.second = second;
        }else{
            throw new IllegalArgumentException("Invalid Seconds Value");
        }            

    }
    catch (IllegalArgumentException exception) {
        System.out.println("Invalid entry");
    }
}  

Answer 3

you need to update your code handle outside range values

eg:

if (hour > 0 && hour < 23 )
    this.hour = hour;
else
    throw new IllegalArgumentException();