java - 如何最大限度地减少输入异常

Question

我有以下代码，它可以很好地完成工作，但正如您所看到的，它非常冗长并且可能令人困惑:

private void addRecord() {
    String firstName = JOptionPane.showInputDialog("First Name: ");
    if (firstName.length() <= 0){
        JOptionPane.showMessageDialog(null, "That is not a valid input.","Input error",JOptionPane.ERROR_MESSAGE);
        addRecord();
    }//end if

    String lastName = JOptionPane.showInputDialog("Last Name: ");
    if (lastName.length() <= 0){
        JOptionPane.showMessageDialog(null, "That is not a valid input.","Input error",JOptionPane.ERROR_MESSAGE);
        addRecord();
    }//end if

    String a = JOptionPane.showInputDialog("Student Number: ");
    int studentNumber = Integer.parseInt(a);
    if (a.length() <= 0 || studentNumber == 0){
        JOptionPane.showMessageDialog(null, "That is not a valid input.","Input error",JOptionPane.ERROR_MESSAGE);
        sortMenu();
    }//end if

    String major = JOptionPane.showInputDialog("Major: ");
    if (major.length() <= 0){
        JOptionPane.showMessageDialog(null, "That is not a valid input.","Input error",JOptionPane.ERROR_MESSAGE);
        addRecord();
    }//end if

    String b = JOptionPane.showInputDialog("GPA: ");
    double gpa = Double.parseDouble(b);
    if (b.length() <= 0 || gpa > 4.0){
        JOptionPane.showMessageDialog(null, "That is not a valid input.","Input error",JOptionPane.ERROR_MESSAGE);
        sortMenu();
    }//end if

    tree.addNode(studentNumber, firstName, lastName, major, gpa);
}//end addRecord

有没有更好的方法可以让我编写此代码来检查每个输入，而不必为每个输入都添加 if 语句？我想尽可能地减少这种情况。

Answer 1

试试这个:

private void checkString(String st, boolean or) {
    if (st.length() <= 0 || or){
        JOptionPane.showMessageDialog(null, "That is not a valid input.","Input error",JOptionPane.ERROR_MESSAGE);
        addRecord();
    }
}
private void addRecord() {
    String firstName = JOptionPane.showInputDialog("First Name: ");
    checkString(firstName, false);

    String lastName = JOptionPane.showInputDialog("Last Name: ");
    checkString(lastName, false);

    String a = JOptionPane.showInputDialog("Student Number: ");
    int studentNumber = Integer.parseInt(a);
    checkString(a, studentNumber == 0);

    String major = JOptionPane.showInputDialog("Major: ");
    checkString(major, false);

    String b = JOptionPane.showInputDialog("GPA: ");
    double gpa = Double.parseDouble(b);
    checkString(b, gpa > 4.0);

    tree.addNode(studentNumber, firstName, lastName, major, gpa);
}

包含 or 参数用于额外条件。