Question

您好，我正在制作一个java工作，出于某种原因，当我在对话框中单击“否”时它到达了if else，它不会退出，而是继续询问学生姓名`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（即0）的值复制到您的welcome中，稍后您将其与JOptionPane.YES_OPTION进行比较，0==0也是0 if将始终为true，因此showConfirmDialog块将始终执行。

int将为您提供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){结果，您必须将其存储在某个变量中，因此请像这样使用

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单击否时系统不退出

1 个答案: