要执行电子邮件验证，我们有很多方法，但简单和最简单的方法是 两种方法 。

1- 使用EditText(....).addTextChangedListenerwhich 不断触发EditText boxie
email_id 中的每个输入无效或有效

/**
 * Email Validation ex:- tech@end.com
*/


final EditText emailValidate = (EditText)findViewById(R.id.textMessage);

final TextView textView = (TextView)findViewById(R.id.text);

String email = emailValidate.getText().toString().trim();

String emailPattern = "[a-zA-Z0-9._-]+@[a-z]+\\.+[a-z]+";

emailValidate .addTextChangedListener(new TextWatcher() { 
    public void afterTextChanged(Editable s) {

    if (email.matches(emailPattern) && s.length() > 0)
        { 
            Toast.makeText(getApplicationContext(),"valid email address",Toast.LENGTH_SHORT).show();
            // or
            textView.setText("valid email");
        }
        else
        {
             Toast.makeText(getApplicationContext(),"Invalid email address",Toast.LENGTH_SHORT).show();
            //or
            textView.setText("invalid email");
        }
    } 
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    // other stuffs 
    } 
    public void onTextChanged(CharSequence s, int start, int before, int count) {
    // other stuffs 
    } 
});

2-if-else使用条件的 最简单方法。使用 getText() 获取 EditText
框字符串并与为电子邮件提供的模式进行比较。如果模式不匹配或不匹配，按钮的 onClick 会显示一条消息。它不会在 EditText
框中的每个字符输入时触发。如下所示的简单示例。

final EditText emailValidate = (EditText)findViewById(R.id.textMessage);

final TextView textView = (TextView)findViewById(R.id.text);

String email = emailValidate.getText().toString().trim();

String emailPattern = "[a-zA-Z0-9._-]+@[a-z]+\\.+[a-z]+";

// onClick of button perform this simplest code.
if (email.matches(emailPattern))
{
Toast.makeText(getApplicationContext(),"valid email address",Toast.LENGTH_SHORT).show();
}
else 
{
Toast.makeText(getApplicationContext(),"Invalid email address", Toast.LENGTH_SHORT).show();
}