Question

我有一个名为ShowBoardList的类，我检查用户是否已登录。如果用户尚未登录，那么我想返回 MainActivity ，它为用户提供登录的按钮不同的服务。

我的 AndroidManifests.xml 如下所示：

<application
   <activity android:name="im.chaitanya.TaskTimer.MainActivity" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name="im.chaitanya.TaskTimer.WebViewActivity" >
    </activity>
    <activity android:name="im.chaitanya.TaskTimer.ShowBoardList"
        android:label="Your Tasks">
    </activity>
</application>

ShowBoardList.java 如下所示：

...
Intent mainActivityIntent = new Intent(ShowBoardList.this, im.chaitanya.TaskTimer.MainActivity.class);
Intent intent = getIntent();
String url = intent.getStringExtra(WebViewActivity.EXTRA_MESSAGE); //url can be null here
Keys keys = new Keys(); //this gets an API key

SharedPreferences settings = getSharedPreferences("mySettings", 0);
String savedToken = settings.getString("token", "Empty");

if (MyUtils.equalsWithNulls(url,"tasktimer://oauthresponse#token=")) {
    Log.d("From ME:", "I've reached inside url check");
    mainActivityIntent.putExtra(caller, "ShowBoardList");
    //caller is a String. I'm storing the name of the current activity (ShowBoardList) in it. 
    //So that the main activity (which I'm trying to call) will know where the call came from.
    startActivity(mainActivityIntent);
}

if(savedToken.equals("Empty") || savedToken.equals("")) {
    String searchString = "#token=";
    int tokenIndex = url.indexOf(searchString) + searchString.length(); //Since url can be null there can be an error here
    String token = url.substring(tokenIndex);
    savedToken = token;
    SharedPreferences.Editor editor = settings.edit();
    editor.putString("token", token);
    editor.apply();
}
...

Condtion equalsWithNulls 检查网址是 null 还是等于参数中的字符串。我在那里有日志语句来检查控件是否到达if语句内部。然而，主要活动没有开始。

编辑： MainActivity.java 的onCreate（）如下所示：

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    SharedPreferences settings = getSharedPreferences("mySettings", 0);
    String token = settings.getString("token", "Empty");
    Intent intent = new Intent(this, ShowBoardList.class);

    if(token != "Empty") {
        startActivity(intent);
    }

    intent = getIntent();
    String callerActivity = intent.getStringExtra(ShowBoardList.caller);
    View coordinatorLayoutView = findViewById(R.id.snackbarPosition);

    if (callerActivity!=null && callerActivity == "ShowBoardList") {
        Snackbar
                .make(coordinatorLayoutView, "Permission Denied", Snackbar.LENGTH_LONG)
                .show();
    }
    setContentView(R.layout.activity_main);
}

Answer 1

尝试在您需要的任何地方定义新的意图。

Intent newIntent = new Intent(ShowBoardList.this, im.chaitanya.TaskTimer.MainActivity.class);
newIntent .putExtra(caller, "ShowBoardList");

startActivity(newIntent );

Answer 2

我的解决方案基于Sourabh对此问题的评论。我从我的日志中意识到活动确实正在开始。

我没有意识到，当startActivity()被调用时，调用活动（在这种情况下为ShowBoardList）暂停，当再次调用ShowBoardList时，它将恢复来自startActivity()之后。

因此，此处的解决方案是在startActivity（）之后立即调用finish()然后调用return，以确保下次调用onCreate。如果有人处于相同的情况，我希望这是有道理的。

这些问题帮助我更多地了解finish()：

about finish() in android

onCreate flow continues after finish()

startActivity（）不会启动活动

2 个答案: