Question

我正在建立一个数据库，我想防止用户输入空文本。我该怎么办？下面的代码有什么问题？

public void AddData () {
        addbtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                    if (name != null && surname != null && marks != null) {

                    String name1 = name.getText().toString();
                    String surname1 = surname.getText().toString();
                    String marks1 = marks.getText().toString();

                    boolean isInserted = mydb.insertdata(name1, surname1, marks1);

                    if (isInserted) {
                        Toast.makeText(MainActivity.this, "Data entered successfully", Toast.LENGTH_LONG).show();
                    } else {
                        Toast.makeText(MainActivity.this, "Failed to enter Data", Toast.LENGTH_LONG).show();
                    }

                    }else if (name == null && surname == null && marks == null)  {
                        Toast.makeText(MainActivity.this, "Please enter Data", Toast.LENGTH_LONG).show();
                    }
            }
        });

}

Answer 1

您只想检查字符串的长度。

public void AddData () {
        addbtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {



                    String name1 = name.getText().toString();
                    String surname1 = surname.getText().toString();
                    String marks1 = marks.getText().toString();

                    if (name1.length() > 0 && surname1.length() > 0 && marks.length() > 0) {

                    boolean isInserted = mydb.insertdata(name1, surname1, marks1);

                    if (isInserted) {
                        Toast.makeText(MainActivity.this, "Data entered successfully", Toast.LENGTH_LONG).show();
                    } else {
                        Toast.makeText(MainActivity.this, "Failed to enter Data", Toast.LENGTH_LONG).show();
                    }

                    }else if (name == null && surname == null && marks == null)  {
                        Toast.makeText(MainActivity.this, "Please enter Data", Toast.LENGTH_LONG).show();
                    }
            }
        });

}

您还可以编写一个函数来为您验证输入内容

private boolean validateInput(String input) {

    if(input == null)
        return false;

    if( input.length == 0)
        return false;


    //... Other validation checks

    return true;
}

但是您不只是想根据长度来验证数据。输入验证应反映您期望的数据类型。例如，如果您要查找电话号码，则应删除不属于电话号码的所有字符。您不希望有人在您的电话号码输入字段中输入他们的电子邮件地址。

Answer 2

我们考虑使用Guava library和方法isNullOrEmpty，它非常有用。

如何防止用户输入空文本？

2 个答案: