先决条件: Android中带有示例的Java的EditText小部件
需要电子邮件验证以通知用户用户输入的电子邮件格式无效。如果用户未以错误的格式输入电子邮件,则将为EditText给出错误字段。在本文中,已逐步讨论了如何在Android中实现电子邮件验证程序。请看以下图片,以了解本文讨论的内容。注意,我们将使用Java语言实现该项目。
在Android中实现电子邮件验证程序的步骤
步骤1:创建一个空的活动项目
- 创建一个空的活动Android Studio项目。选择Java作为编程语言。
- 要了解如何创建一个空的活动Android Studio项目,请参阅Android |如何在Android Studio中创建/启动新项目?
步骤2:使用activity_main.xml文件
- 在应用程序的主布局中,仅实现了两个小部件。一个是“电子邮件编辑文本”字段,另一个是按钮,单击该按钮时将检查输入的电子邮件。
- 在activity_main.xml文件中调用以下代码以实现UI布局。
XML
Java
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Patterns;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
// EditText filed for Email
EditText etMail;
// Button to validate the Email address
Button bValidate;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// register all the UI elements
// with their appropriate IDs
etMail = findViewById(R.id.emailField);
bValidate = findViewById(R.id.validateButton);
// handle the VALIDATE button to show the toast
// message whether the entered email is valid or not
bValidate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
emailValidator(etMail);
}
});
}
// the function which triggered when the VALIDATE button is clicked
// which validates the email address entered by the user
public void emailValidator(EditText etMail) {
// extract the entered data from the EditText
String emailToText = etMail.getText().toString();
// Android offers the inbuilt patterns which the entered
// data from the EditText field needs to be compared with
// In this case the the entered data needs to compared with
// the EMAIL_ADDRESS, which is implemented same below
if (!emailToText.isEmpty() && Patterns.EMAIL_ADDRESS.matcher(emailToText).matches()) {
Toast.makeText(this, "Email Verified !", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this, "Enter valid Email address !", Toast.LENGTH_SHORT).show();
}
}
}
输出界面:
步骤3:使用MainActivity。 Java文件
- 在这种情况下,模式EMAIL_ADDRESS用于演示。
- 但是,还有5种模式可以验证用户的输入。那些是:
DOMAIN_NAME, IP_ADDRESS, PHONE, TOP_LEVEL_DOMAIN, WEB_URL.
- 有关Android中预定义模式的更多信息,请参考模式。
- 在MainActivity中调用以下代码。在这种情况下,用于实现电子邮件验证程序的Java文件。添加了注释以便更好地理解。
Java
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Patterns;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
// EditText filed for Email
EditText etMail;
// Button to validate the Email address
Button bValidate;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// register all the UI elements
// with their appropriate IDs
etMail = findViewById(R.id.emailField);
bValidate = findViewById(R.id.validateButton);
// handle the VALIDATE button to show the toast
// message whether the entered email is valid or not
bValidate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
emailValidator(etMail);
}
});
}
// the function which triggered when the VALIDATE button is clicked
// which validates the email address entered by the user
public void emailValidator(EditText etMail) {
// extract the entered data from the EditText
String emailToText = etMail.getText().toString();
// Android offers the inbuilt patterns which the entered
// data from the EditText field needs to be compared with
// In this case the the entered data needs to compared with
// the EMAIL_ADDRESS, which is implemented same below
if (!emailToText.isEmpty() && Patterns.EMAIL_ADDRESS.matcher(emailToText).matches()) {
Toast.makeText(this, "Email Verified !", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this, "Enter valid Email address !", Toast.LENGTH_SHORT).show();
}
}
}
输出:在模拟器上运行
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