Question

有关如何让我的应用在图片中进行此类验证的任何建议或意见？

enter image description here

Answer 1

首先，我认为您的全局布局必须是RelativeLayout，因此您可以将图片放在EditExt下方，并放在右侧。

然后，您希望在onTextChangedListener上实施EditText，如下所示：

yourEditText.addTextChangedListener(new TextWatcher() {
            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                //test here if s.equal(""); and set your image's visibility
            }

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

            @Override
            public void afterTextChanged(Editable s) {
            }
        });

如果您的文字为空，只需将图片的可见性设置为GONE，否则设置为VISIBLE。

Answer 2

使用Android对象模板：

右键单击要添加代码组件的Android应用程序的项目文件夹。选择新建＆gt;其他... 选择Android＆gt; Android对象，然后单击“下一步”。然后选择登录活动。

要显示错误，请执行以下操作： -

userName.setError("This field is required");

参考此示例： -

    package com.example.login;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.annotation.TargetApi;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.View;
import android.view.inputmethod.EditorInfo;
import android.widget.EditText;
import android.widget.TextView;

/**
 * Activity which displays a login screen to the user, offering registration as
 * well.
 */
public class LoginActivity extends Activity {
    /**
     * A dummy authentication store containing known user names and passwords.
     * TODO: remove after connecting to a real authentication system.
     */
    private static final String[] DUMMY_CREDENTIALS = new String[] {
            "foo@example.com:hello", "bar@example.com:world" };

    /**
     * The default email to populate the email field with.
     */
    public static final String EXTRA_EMAIL = "com.example.android.authenticatordemo.extra.EMAIL";

    /**
     * Keep track of the login task to ensure we can cancel it if requested.
     */
    private UserLoginTask mAuthTask = null;

    // Values for email and password at the time of the login attempt.
    private String mEmail;
    private String mPassword;

    // UI references.
    private EditText mEmailView;
    private EditText mPasswordView;
    private View mLoginFormView;
    private View mLoginStatusView;
    private TextView mLoginStatusMessageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_login);

        // Set up the login form.
        mEmail = getIntent().getStringExtra(EXTRA_EMAIL);
        mEmailView = (EditText) findViewById(R.id.email);
        mEmailView.setText(mEmail);

        mPasswordView = (EditText) findViewById(R.id.password);
        mPasswordView
                .setOnEditorActionListener(new TextView.OnEditorActionListener() {
                    @Override
                    public boolean onEditorAction(TextView textView, int id,
                            KeyEvent keyEvent) {
                        if (id == R.id.login || id == EditorInfo.IME_NULL) {
                            attemptLogin();
                            return true;
                        }
                        return false;
                    }
                });

        mLoginFormView = findViewById(R.id.login_form);
        mLoginStatusView = findViewById(R.id.login_status);
        mLoginStatusMessageView = (TextView) findViewById(R.id.login_status_message);

        findViewById(R.id.sign_in_button).setOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        attemptLogin();
                    }
                });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);
        getMenuInflater().inflate(R.menu.login, menu);
        return true;
    }

    /**
     * Attempts to sign in or register the account specified by the login form.
     * If there are form errors (invalid email, missing fields, etc.), the
     * errors are presented and no actual login attempt is made.
     */
    public void attemptLogin() {
        if (mAuthTask != null) {
            return;
        }

        // Reset errors.
        mEmailView.setError(null);
        mPasswordView.setError(null);

        // Store values at the time of the login attempt.
        mEmail = mEmailView.getText().toString();
        mPassword = mPasswordView.getText().toString();

        boolean cancel = false;
        View focusView = null;

        // Check for a valid password.
        if (TextUtils.isEmpty(mPassword)) {
            mPasswordView.setError(getString(R.string.error_field_required));
            focusView = mPasswordView;
            cancel = true;
        } else if (mPassword.length() < 4) {
            mPasswordView.setError(getString(R.string.error_invalid_password));
            focusView = mPasswordView;
            cancel = true;
        }

        // Check for a valid email address.
        if (TextUtils.isEmpty(mEmail)) {
            mEmailView.setError(getString(R.string.error_field_required));
            focusView = mEmailView;
            cancel = true;
        } else if (!mEmail.contains("@")) {
            mEmailView.setError(getString(R.string.error_invalid_email));
            focusView = mEmailView;
            cancel = true;
        }

        if (cancel) {
            // There was an error; don't attempt login and focus the first
            // form field with an error.
            focusView.requestFocus();
        } else {
            // Show a progress spinner, and kick off a background task to
            // perform the user login attempt.
            mLoginStatusMessageView.setText(R.string.login_progress_signing_in);
            showProgress(true);
            mAuthTask = new UserLoginTask();
            mAuthTask.execute((Void) null);
        }
    }

    /**
     * Shows the progress UI and hides the login form.
     */
    @TargetApi(Build.VERSION_CODES.HONEYCOMB_MR2)
    private void showProgress(final boolean show) {
        // On Honeycomb MR2 we have the ViewPropertyAnimator APIs, which allow
        // for very easy animations. If available, use these APIs to fade-in
        // the progress spinner.
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
            int shortAnimTime = getResources().getInteger(
                    android.R.integer.config_shortAnimTime);

            mLoginStatusView.setVisibility(View.VISIBLE);
            mLoginStatusView.animate().setDuration(shortAnimTime)
                    .alpha(show ? 1 : 0)
                    .setListener(new AnimatorListenerAdapter() {
                        @Override
                        public void onAnimationEnd(Animator animation) {
                            mLoginStatusView.setVisibility(show ? View.VISIBLE
                                    : View.GONE);
                        }
                    });

            mLoginFormView.setVisibility(View.VISIBLE);
            mLoginFormView.animate().setDuration(shortAnimTime)
                    .alpha(show ? 0 : 1)
                    .setListener(new AnimatorListenerAdapter() {
                        @Override
                        public void onAnimationEnd(Animator animation) {
                            mLoginFormView.setVisibility(show ? View.GONE
                                    : View.VISIBLE);
                        }
                    });
        } else {
            // The ViewPropertyAnimator APIs are not available, so simply show
            // and hide the relevant UI components.
            mLoginStatusView.setVisibility(show ? View.VISIBLE : View.GONE);
            mLoginFormView.setVisibility(show ? View.GONE : View.VISIBLE);
        }
    }

    /**
     * Represents an asynchronous login/registration task used to authenticate
     * the user.
     */
    public class UserLoginTask extends AsyncTask<Void, Void, Boolean> {
        @Override
        protected Boolean doInBackground(Void... params) {
            // TODO: attempt authentication against a network service.

            try {
                // Simulate network access.
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                return false;
            }

            for (String credential : DUMMY_CREDENTIALS) {
                String[] pieces = credential.split(":");
                if (pieces[0].equals(mEmail)) {
                    // Account exists, return true if the password matches.
                    return pieces[1].equals(mPassword);
                }
            }

            // TODO: register the new account here.
            return true;
        }

        @Override
        protected void onPostExecute(final Boolean success) {
            mAuthTask = null;
            showProgress(false);

            if (success) {
                finish();
            } else {
                mPasswordView
                        .setError(getString(R.string.error_incorrect_password));
                mPasswordView.requestFocus();
                }
            }



        @Override
        protected void onCancelled() {
            mAuthTask = null;
            showProgress(false);
        }
    }
}


    <merge xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context=".LoginActivity" >

    <!-- Login progress -->

    <LinearLayout
        android:id="@+id/login_status"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:gravity="center_horizontal"
        android:orientation="vertical"
        android:visibility="gone" >

        <ProgressBar
            style="?android:attr/progressBarStyleLarge"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="8dp" />

        <TextView
            android:id="@+id/login_status_message"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="16dp"
            android:fontFamily="sans-serif-light"
            android:text="@string/login_progress_signing_in"
            android:textAppearance="?android:attr/textAppearanceMedium" />
    </LinearLayout>

    <!-- Login form -->

    <ScrollView
        android:id="@+id/login_form"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >

        <LinearLayout
            style="@style/LoginFormContainer"
            android:orientation="vertical" >

            <EditText
                android:id="@+id/email"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="@string/prompt_email"
                android:inputType="textEmailAddress"
                android:maxLines="1"
                android:singleLine="true" />

            <EditText
                android:id="@+id/password"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="@string/prompt_password"
                android:imeActionId="@+id/login"
                android:imeActionLabel="@string/action_sign_in_short"
                android:imeOptions="actionUnspecified"
                android:inputType="textPassword"
                android:maxLines="1"
                android:singleLine="true" />

            <Button
                android:id="@+id/sign_in_button"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="right"
                android:layout_marginTop="16dp"
                android:paddingLeft="32dp"
                android:paddingRight="32dp"
                android:text="@string/action_sign_in_register" />
        </LinearLayout>
    </ScrollView>

</merge>

Android登录验证 - 图片

2 个答案: