Question

我的启动器活动是loginActivity，我希望当用户选择大学并第二次打开应用程序时，他应该转移到另一个活动TestYip（而不是登录活动）。这是启动器激活应该在用户登录后更改。为此我在select_Collage活动中创建了一个函数getCollege，该活动是从loginActivity调用的。但它不起作用..代码给出：

Select_Collage

            package notes.test.firebase;

    import java.util.ArrayList;
    import java.util.HashMap;

    import android.content.Intent;
    import android.content.SharedPreferences;
    import android.os.Build;
    import android.os.Bundle;
    import android.preference.PreferenceManager;
    import android.support.v7.app.AppCompatActivity;
    import android.text.Editable;
    import android.text.TextWatcher;
    import android.view.View;
    import android.view.Window;
    import android.view.WindowManager;
    import android.widget.AdapterView;
    import android.widget.ArrayAdapter;
    import android.widget.EditText;
    import android.widget.ListView;
    import android.widget.TextView;


    public class Select_Collage extends AppCompatActivity {

        // List view
        public ListView lv;
        public TextView tv;
        public String str;


        // Listview Adapter
        ArrayAdapter<String> adapter;

        // Search EditText
        EditText inputSearch;

       final String products[] = {"Jaypee university Guna", "Delhi university", "Graphics era", "UPES",
                "Amity university", "Saradha university",
                "ITM gwalior", "RKDF university", "Indraprast university", "IIT delhi"};


        // ArrayList for Listview
        ArrayList<HashMap<String, String>> productList;

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.collage);
            if (Build.VERSION.SDK_INT >= 21) {
                Window window = getWindow();
                window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
                window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
                window.setStatusBarColor(getResources().getColor(R.color.colorPrimaryDark));
            }
            // Listview Data
           /* final String products[] = {"Jaypee university Guna", "Delhi university", "Graphics era", "UPES",
                    "Amity university", "Saradha university",
                    "ITM gwalior", "RKDF university", "Indraprast university", "IIT delhi"};

    */
            lv = (ListView) findViewById(R.id.list_view);


            inputSearch = (EditText) findViewById(R.id.inputSearch);

            // Adding items to listview
            adapter = new ArrayAdapter<String>(this, R.layout.college_selection_text_view, R.id.product_name, products);
            lv.setAdapter(adapter);

            lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> arg0, View arg1, int position,
                                        long arg3){

                    tv = (TextView) arg1.findViewById(R.id.product_name);

                    str = tv.getText().toString().trim();

                    if (str.equals(products[0]))

                    {
                        Intent int0 = new Intent(Select_Collage.this, TestYip.class);
                        startActivity(int0);
                    }

                    else if(str.equals(products[1])) {
                        Intent int1 = new Intent(Select_Collage.this, MainListDisplay.class);
                        startActivity(int1);

                    }
                }
            });
            /**
             * Enabling Search Filter
             * */
            inputSearch.addTextChangedListener(new TextWatcher() {

                @Override
                public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
                    // When user changed the Text
                    Select_Collage.this.adapter.getFilter().filter(cs);
                }

                @Override
                public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
                                              int arg3) {
                    // TODO Auto-generated method stub

                }

                @Override
                public void afterTextChanged(Editable arg0) {
                    // TODO Auto-generated method stub
                }


            });
                }

        public void getCollege () {
            SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
            SharedPreferences.Editor editor = preferences.edit();
            if (str.equals(products[0]))
            {
                editor.putInt("key", 1);
                editor.apply();
                //Intent int0 = new Intent(getAppl,TestYip.class);
                //Intent int0 = new Intent(getApplicationContext(),TestYip.class);
                //startActivity(int0);
            } else {
                editor.putInt("key", 0);
                editor.apply();
            }
        }
    }

LoginActivity

package notes.test.firebase;

import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.Toast;

import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;

public class LoginActivity extends AppCompatActivity {

    private EditText inputEmail, inputPassword;
    private FirebaseAuth auth;
    private ProgressBar progressBar;
    private Button btnSignup, btnLogin, btnReset;

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

        //Get Firebase auth instance
        auth = FirebaseAuth.getInstance();

        if (auth.getCurrentUser() != null ) {
            Select_Collage s = new Select_Collage();
            //s.getCollege();
            //startActivity(new Intent(LoginActivity.this, MainActivity.class));
            s.getCollege();
            SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
            int i = preferences.getInt("key",0);
            ///startActivity(new Intent(LoginActivity.this, MainActivity.class));
            if (i==1)
            {
                startActivity(new Intent(LoginActivity.this, TestYip.class));
            }
            else
                startActivity(new Intent(LoginActivity.this, MainActivity.class));


        }

        // set the view now
        setContentView(R.layout.activity_login);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        inputEmail = (EditText) findViewById(R.id.email);
        inputPassword = (EditText) findViewById(R.id.password);
        progressBar = (ProgressBar) findViewById(R.id.progressBar);
        btnSignup = (Button) findViewById(R.id.btn_signup);
        btnLogin = (Button) findViewById(R.id.btn_login);
        btnReset = (Button) findViewById(R.id.btn_reset_password);

        //Get Firebase auth instance
        auth = FirebaseAuth.getInstance();

        btnSignup.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(LoginActivity.this, SignupActivity.class));
            }
        });

        btnReset.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(LoginActivity.this, ResetPasswordActivity.class));
            }
        });

        btnLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String email = inputEmail.getText().toString();
                final String password = inputPassword.getText().toString();

                if (TextUtils.isEmpty(email)) {
                    Toast.makeText(getApplicationContext(), "Enter email address!", Toast.LENGTH_SHORT).show();
                    return;
                }

                if (TextUtils.isEmpty(password)) {
                    Toast.makeText(getApplicationContext(), "Enter password!", Toast.LENGTH_SHORT).show();
                    return;
                }

                progressBar.setVisibility(View.VISIBLE);

                //authenticate user
                auth.signInWithEmailAndPassword(email, password)
                        .addOnCompleteListener(LoginActivity.this, new OnCompleteListener<AuthResult>() {
                            @Override
                            public void onComplete(@NonNull Task<AuthResult> task) {
                                // If sign in fails, display a message to the user. If sign in succeeds
                                // the auth state listener will be notified and logic to handle the
                                // signed in user can be handled in the listener.
                                progressBar.setVisibility(View.GONE);
                                if (!task.isSuccessful()) {
                                    // there was an error
                                    if (password.length() < 6) {
                                        inputPassword.setError(getString(R.string.minimum_password));
                                    } else {
                                        Toast.makeText(LoginActivity.this, getString(R.string.auth_failed), Toast.LENGTH_LONG).show();
                                    }
                                } else {
                                    Intent intent = new Intent(LoginActivity.this, MainActivity.class);
                                    startActivity(intent);
                                    finish();
                                }
                            }
                        });
            }
        });
    }
}

Android Manifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="notes.test.firebase">

    <uses-permission android:name="android.permission.INTERNET" />

    <!-- To auto-complete the email text field in the login form with the user's emails -->
    <uses-permission android:name="android.permission.GET_ACCOUNTS" />
    <uses-permission android:name="android.permission.READ_PROFILE" />
    <uses-permission android:name="android.permission.READ_CONTACTS" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".LoginActivity"
            android:theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".MainActivity"
            android:label="@string/title_activity_profile"
            android:theme="@style/AppTheme.NoActionBar">




        </activity>
        <activity
            android:name=".SignupActivity"
            android:label="@string/title_activity_login"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".ResetPasswordActivity"
            android:label="@string/title_activity_reset_password"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".TestYip"
            android:label="@string/title_test"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity android:name=".Computer_Notes" />
        <activity
            android:name=".MainListDisplay"
            android:label="@string/Select_Subject"
            android:theme="@style/AppTheme.NoActionBar" >
        <meta-data
            android:name="android.app.default_searchable"
            android:value=".SearchResulltsActivity" />
        </activity>
        <activity
            android:name=".Select_Collage"
            android:label="@string/Select_Collage"
            android:theme="@style/AppTheme.NoActionBar">
        <meta-data
            android:name="android.app.default_searchable"
            android:value=".SearchResulltsActivity" />
        </activity>

        <meta-data
            android:name="android.app.searchable"
            android:resource="@xml/searchable" />

        <activity android:name=".SearchResulltsActivity"
                  android:theme="@style/AppTheme.NoActionBar">
            <meta-data android:name="android.support.PARENT_ACTIVITY"
                android:value=".MainActivity"/>
            <intent-filter>
                <action android:name="android.intent.action.SEARCH" />
            </intent-filter>
            <meta-data
                android:name="android.app.searchable"
                android:resource="@xml/searchable" />
        </activity>
    </application>

</manifest>

请告诉我如何根据条件从一项活动转移到另一项活动。

Answer 1

尝试在共享首选项中保存boolean或int。在Select_collage中设置int或boolean 在LoginAcitivity中获取其值，并按照您的方式检查条件。

我猜您的代码问题是在LoginAcitivity中检查条件时，Select_collage活动中的值未设置，因为它未创建。

https://developer.android.com/training/basics/data-storage/shared-preferences.html

Answer 2

不要使用LoginActivity作为启动器活动。在您的LoginActivity中，将一些标志值保存到SharedPreferences以指示用户已登录，然后在您的其他活动的onCreate（将此设置为启动器）中，检查此值，如果它不存在，则转到LoginActivity。

Answer 3

我会推荐最好的方法。每当你遇到这些事情时，Splash屏幕都会帮助你。

让我解释一下： -

只需将启动画面设为启动器活动即可。如果您不想让它显示更长时间，只需让处理程序运行1-2秒。现在看下面的代码。

SplashScreen.java

public class SplashScreen extends AppCompatActivity {

    private String email;

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

        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

        setContentView(R.layout.activity_splash);

        //SharedPreference to Store API Result
        SharedPreferences pref = getApplicationContext().getSharedPreferences("CachedResponse", 0);
        SharedPreferences.Editor editor = pref.edit();
        editor.apply();

        email = pref.getString("login", null);

        int SPLASH_TIME_OUT = 3000;

        if (email != null) {

            //It means User is already Logged in so I will take the user to Select_College Screen

            new Handler().postDelayed(new Runnable() {

                @Override
                public void run() {

                    Intent intent = new Intent(SplashScreen.this, Select_College.class);
                    intent.putExtra("Email", email);
                    startActivity(intent);
                    finish();

                }

            }, SPLASH_TIME_OUT);

        } else {

            //It means User is not Logged in so I will take the user to Login Screen

            new Handler().postDelayed(new Runnable() {

                @Override
                public void run() {

                    Intent intent = new Intent(SplashScreen.this, Login.class);
                    startActivity(intent);
                    finish();

                }

            }, SPLASH_TIME_OUT);

        }

    }
}

Login.java

public class Login extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_doctor_login);

        //SharedPreference to Store API Result
        pref = getApplicationContext().getSharedPreferences("CachedResponse", 0);

        Login();

    }

    private void login() {

        //If login is successfull, before moving to next activity, store something in sharedpreference with name login. It can be email or just a string as "true"

        SharedPreferences.Editor editor = pref.edit();
                        editor.putString("login", email);
                        editor.apply();

                        Intent intent = new Intent(DoctorLogin.this, Select_Collage.class);
                        intent.putExtra("Email", email);
                        startActivity(intent);
                        finish();

    }
}

Select_Collage.java

public class Select_Collage extends AppCompatActivity {

    private SharedPreferences pref;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_doctor_message);

        //SharedPreference to Store API Result
        pref = getApplicationContext().getSharedPreferences("CachedResponse", 0);

        //Somewhere on Signout button click, delete the login sharedpreference
        signOut();

    }

    private void signOut() {

        SharedPreferences.Editor editor = pref.edit();
        editor.remove("login");
        editor.apply();

        Intent intent = new Intent(Select_Collage.this, Login.class);
        startActivity(intent);
        finish();

    }
}

这就是你如何解决这个问题。保持编码：）

Answer 4

你必须开始一个闪屏活动..在那个活动你需要检查条件（oncreate功能）哪个活动应该发布到下一个..

我们可以根据某些条件进行两次发射器活动吗？

4 个答案: