Question

我正在使用EditText，并且有TextWatcher。

我在其中输入数字，如果最后一个文本被删除，我想用0填充该字段。

如何使用TextWatcher的三种方法？

    input.addTextChangedListener(new TextWatcher() {

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count,
                int after) {
        }

        @Override
        public void afterTextChanged(Editable s) {
            double value=Double.parseDouble(input.getText().toString());//here it will throw error if no text there. 
            //I do not only want to catch this exception and do something with it, but I want to detect this event and if it happens I want to try some solution to stop it.
        }
    });

Answer 1

在afterTextChanged方法中......如果要看块是否为空。而不是使用输入编辑框使用您在方法参数中的可编辑的。

if (s.toString()!=null && s.toString().trim().equals("")==false){
   double value=Double.parseDouble(s.getText().toString());
}else{
   double value = 0;
}

Answer 2

您可以这样做：

 @Override
    public void afterTextChanged(Editable s) {
        try {
            double value=Double.parseDouble(s.toString());
            ... //if there is something to do with value
        } catch (NumberFormatException e) {
            s.clear();
            s.insert(0, "0");
            // The method will be recalled since s was changed
        }
    }

使用TextWatcher检测最后删除的文本

2 个答案: