单击否时系统不退出

Question

你好，所以我正在使一个java工作，出于某种原因，当我到达if else时，当我在对话框中单击no时，它没有退出，而是继续询问学生名`public static void main(string[]args){

JFrame frame = new JFrame("Student Record");
JOptionPane.showMessageDialog(frame,
        "Welcome to the School's Student Grade Record!");

System.out.println("School's Student Grade Record");

int welcome = JOptionPane.YES_NO_OPTION;
 JOptionPane.showConfirmDialog 
    (null, "Woild you like to input grades on the students?",
            "Grade",welcome);
 if (welcome == JOptionPane.YES_OPTION){
String name;
String name1 = "";
do {
    name = JOptionPane.showInputDialog("Enter Student's Name");
    if (name.matches("^[a-zA-Z ]*$")){
        name1 = name;
        System.out.println("Student name :" +name1);
    }else{
        JOptionPane.showMessageDialog(frame,"Enter Student name");
    }
    }while (!name.matches("^[a-zA-Z ]*$"));

}else {
     System.exit(0);
} 
}

}`

Answer 1

您的代码只是将joptionpane.yes_no_option(0)的值复制到welcome)中，然后将其与joptionpane.yes_option(0)进行比较，因此0==0将始终为真，因此ifblock将始终执行。

showconfirmdialog将给出一个int结果，您必须将其存储在某个变量中，所以请如下所示

int welcome;

      // store the output result of showConfirmDialog in welcome

      welcome=JOptionPane.showConfirmDialog(null, "Woild you like to input grades on the students?",
                "Grade",JOptionPane.YES_NO_OPTION);

      // compare result with predefined positive value i.e JOptionPane.YES_OPTION
     if (welcome == JOptionPane.YES_OPTION){