空的 EditText 导致程序崩溃

Question

当我的EditText 字段为空时，如何防止我的应用崩溃？

    public class Credits extends Activity {
    int inaugural = 1992;
    int differenceInYears;
    int userGuess;
    Calendar calendar = Calendar.getInstance();
    int year = calendar.get(Calendar.YEAR);
    int output;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_credits);
        final EditText Guess=(EditText)findViewById(R.id.txtYearGuess);
        Button go = (Button)findViewById(R.id.btnCalculate);
        final TextView result = ((TextView)findViewById(R.id.txtResult));

        go.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                int userGuess= Integer.parseInt(Guess.getText().toString());
                differenceInYears = year - inaugural;
                output = userGuess - differenceInYears;

                if (output < -1) {
                    result.setText("Guess again! You guessed too low!");

                    }

                else if (output == 1) {
                    result.setText("You're REALLY close! You guessed too high!");


                    }

                else if (output == -1) {
                    result.setText("You're REALLY close! You guessed too low!");


                    }

                else if (output > 1) {
                    result.setText("Guess again! You guessed too high!");


                    }

                else {
                    result.setText("Good job! You're an FRC Genious!");

                    }



            }

        });
    }

}

是否就像让另一个 if 语句监视“空”变量一样简单？如果是这样，该代码会是什么样子？我对防止这种崩溃发生的想法有点不知所措。如果 Eclipse 有任何类型的报告可以帮助回答这个问题，请告诉我在哪里可以找到它。

谢谢！

编辑

我尝试添加推荐的TextUtils，但没有解决应用崩溃问题。

public class Credits extends Activity {
    int inaugural = 1992;
    int differenceInYears;
    int userGuess;
    Calendar calendar = Calendar.getInstance();
    int year = calendar.get(Calendar.YEAR);
    int output;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_credits);
        final EditText Guess=(EditText)findViewById(R.id.txtYearGuess);
        Button go = (Button)findViewById(R.id.btnCalculate);
        final TextView result = ((TextView)findViewById(R.id.txtResult));

        go.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                int userGuess= Integer.parseInt(Guess.getText().toString());
                differenceInYears = year - inaugural;
                output = userGuess - differenceInYears;

                if(!TextUtils.isEmpty(Guess.getText().toString())) {
                    Toast.makeText(Credits.this, "Please input your Guess", Toast.LENGTH_LONG).show();
                    }

                else {

                if (output < -1) {
                    result.setText("Guess again! You guessed too low!");

                    }

                else if (output == 1) {
                    result.setText("You're REALLY close! You guessed too high!");


                    }

                else if (output == -1) {
                    result.setText("You're REALLY close! You guessed too low!");


                    }

                else if (output > 1) {
                    result.setText("Guess again! You guessed too high!");


                    }

                else {
                    result.setText("Good job! You're an FRC Genious!");

                    }

            }

            }

        });
    }

}

Answer 1

getText().getString() 保证不会返回 null，只要您的 edittext 正确初始化（即它指向实际视图），所以最坏的情况是您会得到一个空字符串 --> ""。要检查这一点，请按照以下方式进行操作

if (!Guess.getText().getString().equals(""))如果获取到的值不等于“”，那就做事。

您可能还希望将解析语句包装在 try-catch 块中，以防止出现人们输入字母或其他内容的情况。

public static Integer tryParse(String text) {
   try {
     return new Integer(text);
   } catch (NumberFormatException e) {
     return null;
   }
}

try/parse 的来源：here

Answer 2

在 onClickListener 的 onClick 方法中添加检查

    String text = Guess.getText().toString();
    if(text != null && !text.trim().equals("")){
       try{
            //Do watever you want to do here
       }catch(NumberFormatException e){
            e.printStackTrace();
       }
    }

您也在进行 int 解析，因此您还可以检查 TextUtils.isDigitsOnly (Doc)