Android Java：通过Java添加到现有XML布局时，按钮和TextViews不显示

Question

OK, I'm tearing my hair out.

I have a simple default relative layout XML for my main activity, and defined a LinearLayout in the XML as well. In my Java code, I added a LinearLayout row, orientation horizontal, and added it to the XML Linearlayout (which I found by ID). When I then added Buttons or Textviews to that layour row, they showed up perfectly.

However, when I attempted to do the same thing in another activity, I can't get the TextViews or Buttons to show up at all. I originally had a background image and tried adding my Buttons and TextViews directly to the root RelativeLayout (foundById), with plans to move them around by .setX and .setY, but I took away the background and reverted to referencing a specific Linearlayout like my main Activity (for testing purposes, to remove any anomalies)and it still won't show them. I have re-arranged and tested forever and can not see what I'm missing.

Here's my current XML (stripped down for testing):

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_open_template"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.mystuff.stupidapp.OpenTemplateActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:id="@+id/openTemplateMain">
    </LinearLayout>

</RelativeLayout>

...and here's the current code (also stripped down):

public class OpenTemplateActivity extends AppCompatActivity {

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

        final Resources res = getResources();
        Intent intent = getIntent();
        String fileName = intent.getStringExtra(MainActivity.EXTRA_FILENAME);

        DisplayMetrics displaymetrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
        int screenHeight = displaymetrics.heightPixels;
        int screenWidth = displaymetrics.widthPixels;

        LinearLayout.LayoutParams rowLayoutParams = new LinearLayout.LayoutParams(
                LinearLayout.LayoutParams.MATCH_PARENT,
                LinearLayout.LayoutParams.MATCH_PARENT, 1.0f);

        LinearLayout llMain = new LinearLayout(this);
        llMain.setOrientation(LinearLayout.HORIZONTAL);
        LinearLayout llMainParent = (LinearLayout) findViewById(R.id.openTemplateMain);
        llMainParent.addView(llMain);

        Button bTest = new Button(this);
        bTest.setText("TESTB");
        llMain.addView(bTest);


        //other code below unrelated.
    }
}

Ideas, anyone? Please?

Answer 1

Answering my own question for those with a similar issue: Turns out the APK was stuck, but only with code. Meaning any changes to the XML template (adding/removing Text or buttons or backgrounds) would reflect on the test device when I hit Play or Debug. But any changes to the code would NOT be reflected. I noticed this when I changed the tags in my debug logging and they were not reflected in the logs. I also noticed a Toast-like popup saying something about the app being dismissed manually and to re-run via IDE, but it didn't stay around long enough for a good look.

Clearing the cache and data, the uninstalling the app, then re-launching via the IDE play, fixed the issue. Code changes are now being reflected as expected, and code-created views are being shown as well.

Answer 2

You can prevent this or something similar from happening in the future by disabling the instant run feature in Android Studio: https://stackoverflow.com/a/35169716/3662251

Instant run basically incrementally compiles your code and only pushes the changes to the device. Unfortunately in its current state inconsistencies between code and runtime happen quite often and can lead to many wasted hours of bug hunting when that bug was actually introduced by instant run.