title: Not checking validation moving to next activity in android
body: <p>Hi In My Application I have username and password and login button.click the login submit button without checking validations and empty fields also moving to next activity.</p>
  
  <p>I want to check whether the username is required and password required clicking login button move to next activity.</p>
  
  <p><strong>Login.java</strong></p>
  
  <pre><code>public class Login extends Activity {
      Button login;
      private static final Pattern USERNAME_PATTERN = Pattern
              .compile("[a-zA-Z0-9]{1,250}");
      private static final Pattern PASSWORD_PATTERN = Pattern
              .compile("[a-zA-Z0-9+_.]{4,16}");
      EditText usname,pword;
      TextView tv;
      String result=null;
      HttpPost httppost;
      StringBuffer buffer;
      HttpResponse response;
      HttpClient httpclient;
      CheckBox mCbShowPwd;
      List&lt;NameValuePair&gt; nameValuePairs;
      ProgressDialog dialog = null;
  
      @Override
      public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.login);
  
          login = (Button)findViewById(R.id.login);  
          usname = (EditText)findViewById(R.id.username);
          pword= (EditText)findViewById(R.id.password);
          mCbShowPwd = (CheckBox) findViewById(R.id.cbShowPwd);
         mCbShowPwd.setOnCheckedChangeListener(new OnCheckedChangeListener() {
  
              public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                  // checkbox status is changed from uncheck to checked.
                  if (!isChecked) {
                          // show password
                      usname.setTransformationMethod(PasswordTransformationMethod.getInstance());
                  } else {
                          // hide password
                       pword.setTransformationMethod(HideReturnsTransformationMethod.getInstance());
                  }
              }
          });
  
         login.setOnClickListener(new OnClickListener() {
              @Override
              public void onClick(View v) {
                  final String username = usname.getText().toString();
                  final String password = pword.getText().toString();
                  if (username.equals("") || password.equals("")) {
                      if (username.equals("")) {
                          Toast.makeText(Login.this, "ENTER USERNAME",
                                  Toast.LENGTH_LONG).show();
  
                      }
                      if (password.equals("")) {
                          Toast.makeText(Login.this, "ENTER PASSWORD",
                                  Toast.LENGTH_LONG).show();
  
                      }
  
                  } else {
                      if (!CheckUsername(username)) {
                          Toast.makeText(Login.this, "ENTER VALID USERNAME",
                                  Toast.LENGTH_LONG).show();
                      }
                      if (!CheckPassword(password)) {
                          Toast.makeText(Login.this, "ENTER VALID PASSWORD",
                                  Toast.LENGTH_LONG).show();
                      }
  
                  }
  
                  final String queryString = "username=" + username + "&amp;password="
                          + password;
                  String result = DatabaseUtility.executeQueryPhp("login",queryString);
  
                   Intent i = new Intent(getApplicationContext(), Home.class);
                      startActivity(i);
  
  
  
  
  
  
  
                          }
                        });
  
  
  
              }
  
              private boolean CheckPassword(String password) {
  
                  return PASSWORD_PATTERN.matcher(password).matches();
              }
  
              private boolean CheckUsername(String username) {
  
                  return USERNAME_PATTERN.matcher(username).matches();
              }
  </code></pre>