java应用程序在尝试验证空字段时崩溃，错误为“无法执行安卓:onClick的方法”

Question

我试图创建空字段验证，如果用户不输入任何字符串/整数，只需按下按钮，他将收到弹出窗口，说明该字段为空

我将感谢任何帮助

见下面我的代码：

...

    public void clickCheck (View view) {
        EditText editText = (EditText) findViewById(R.id.userType);
        Integer userNum = Integer.parseInt(editText.getText().toString());
        String userField = editText.getText().toString().trim();
        String message = "";


        if (userField.isEmpty()) {
            message = "please input something!!!!!";
        } else {
            Shape mynumber = new Shape();
            mynumber.number = userNum;
            if ((mynumber.isSquareNum() == true) && (mynumber.isTriangularNum() == false)) {

                makeToast("The number " + userNum + " is a Square number.");
            } else if ((mynumber.isSquareNum() == false) && (mynumber.isTriangularNum() == true)) {
                makeToast("The number " + userNum + " is a Triangular number.");
            } else if ((mynumber.isSquareNum() == false) && (mynumber.isTriangularNum() == false)) {
                makeToast("The number " + userNum + " is a not Square or Triangular shape");
            } else if ((mynumber.isSquareNum() == true) && (mynumber.isTriangularNum() == true)) {
                makeToast("The number " + userNum + " is both Square & Triangular shapes");
            }

        }
    }


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}

Answer 1

谢谢@Hakob你的建议很有效。 事后我的问题是因为我的Toast命令没有正确定义

所以我有这样一条消息：“请输入一些东西！”

我改为：makeToast（“请输入一些东西！！！”）

实际上，我根本没有定义Toast命令，所以应用程序不理解它应该弹出一条消息：）

再次感谢你的帮助

Answer 2

这个问题与

Integer userNum = Integer.parseInt(editText.getText().toString());

它可能会抛出NumberFormatException，直到验证后才能到达

你可以这样试试

    public void clickCheck (View view) {
        EditText editText = (EditText) findViewById(R.id.userType);
        String userField = editText.getText().toString().trim();
        String message = "";
        if (userField.isEmpty()) {
            message = "please input something!!!!!";
        } else {
            Shape mynumber = new Shape();
            Integer userNum;
            try {
                userNum = Integer.parseInt(editText.getText().toString());
            }catch (NumberFormatException ex) {
                message = "Not an integer";
            }
            mynumber.number = userNum;
            ...
        }
    }