Android 检查之前登录过的用户，否则开始登录活动 [英] Android check user logged in before, else start login activity

问题描述

我希望在用户启动应用程序但之前未登录时启动登录活动.如果之前已成功登录，应用程序将跳过登录页面并移至 MainMenu.java.我现在拥有的是:

 public class Login extends Activity 实现 OnClickListener, TaskCompleteCallback{first_time_check();...@覆盖protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.configure);...}私人布尔 first_time_check() {String first = mPreferences.getString("first", null);if((第一个==空)){Intent i = new Intent(Login.this, MainMenu.class);开始活动(i);}返回假；}...SharedPreferences.Editor 编辑器 = mPreferences.edit();editor.putString("first", value);...editor.commit();//关闭活动Intent i = new Intent(Login.this, MainMenu.class);开始活动(i);}

但我得到了 FC.我实现 SharedPreferences 的方式有问题吗?

解决方案

您的代码只是从不调用 first_time_check()，因此在返回用户的情况下自动转发不起作用.

你可以在 onCreate() 中做

protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);first_time_check();setContentView(R.layout.configure);...}

因此对于新用户，first_time_check() 会将他转发到登录页面，否则将显示当前布局，他可以在此页面上继续.

I want the login activity to start when the user starts the app but has not logged in before. If a successful login has been completed before, the app will skip the login page and move to MainMenu.java. What I have now is:

    public class Login extends Activity implements OnClickListener, TaskCompleteCallback{

     first_time_check();

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

    ...}

private boolean first_time_check() {    
    String first = mPreferences.getString("first", null);
        if((first == null)){
            Intent i = new Intent(Login.this, MainMenu.class);
             startActivity(i);
        }
        return false;
    }

...
        SharedPreferences.Editor editor = mPreferences.edit();
        editor.putString("first", value);
    ...

        editor.commit();        

        // Close the activity
        Intent i = new Intent(Login.this, MainMenu.class);
         startActivity(i);
    }           

But I get FCs'. Is something wrong with how I implemented SharedPreferences?

解决方案

Your code just never calls that first_time_check(), thus the automatic forward in case of a returning user does not work.

You could in onCreate() do

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

    first_time_check();

    setContentView(R.layout.configure);

    ...}

So for a new user, first_time_check() would forward him to the login page, otherwise the current layout would be shown and he could continue on this page.

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