java - 取消按钮必须有一个功能

Question

这个取消按钮有问题。

使用这些代码：

int deposit;
String dep =
   JOptionPane.showInputDialog("How much would you like to deposit?\n\t$: ");
deposit = Integer.parseInt(dep);

应该会出现一个“确定”和“取消”按钮，但是每当我单击取消按钮时，根本没有任何响应。我想要的是，每当我点击“取消”按钮时，它应该让我回到主菜单，但是如何呢？

编码：

private static void processDeposit(String num, int rc){
    int deposit;
    String dep =
        JOptionPane.showInputDialog(
            "How much would you like to deposit?\n\t$: ");
    deposit = Integer.parseInt(dep);
    JOptionPane.showMessageDialog(
        null, "You have deposited $" + dep + " into the account of " + name);
    myAccount.setBalance(myAccount.getBalance() + deposit);
}

Answer 1

如果用户单击取消 dep 将返回为 null

所以你可以这样做：

 if(input == null || (input != null && ("".equals(input))))   
 {

         //what you ever you need to do here

 }

Answer 2

尝试这个：

private static void processDeposit(String num, int rc) {
    int deposit;
    String dep =
            JOptionPane.showInputDialog(
                    "How much would you like to deposit?\n\t$: ");
    if (dep == null || dep.equals("")) {  // cancel pressed
        JOptionPane.getRootFrame().dispose(); // close dialog
    } else {
        deposit = Integer.parseInt(dep);  // no else or try/catch = NFE exception
        JOptionPane.showMessageDialog(
                null, "You have deposited $" + dep + " into the account of " + name);
        myAccount.setBalance(myAccount.getBalance() + deposit);
    }

}