findViewById return null, when export a project to jar file and import it into my project

Question

I export a third party project to a jar file and set this project as a Library, then import it into my project. All"@+id" in xml files under folder layout have been modified to"@id". And I added ids.xml& public.xml file in the third party project. Mainifest.xml is added too.

In my project,code like that it.setClass(this, ActivityImageDetail.class); It actually run into ActivityImageDetail.class, which is the third party class in jar file.

But when it execute layout = (LinearLayout) findViewById(R.id.***); I got Null.

Logcat said java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mytest/com.MobileVisualSearch.ActivityImageDetail}: java.lang.NullPointerException

It seems that all findViewById() in the third-party class return null.

How could I fix it?

Answer 1

Sadly, you can't use JAR files to store Android resources. The generated R.java will not contain informations from the JAR file.

Answer 2

Could you post the code around the following line?

layout = (LinearLayout) findViewById(R.id.***);

Did you inflate the layout file before trying to get a particular id from it?

I made a small project that consumes a layout from a library in the following way:

View view = inflater.inflate(R.layout.imported_layout, container, false);
TextView textView = (TextView) view.findViewById(R.id.imported_textview);

textView.setText("Hey, I'm an imported TextView");

And imported_layout.xml is just a very simple layout:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/imported_textview"
        android:layout_width="wrap_content"
        android:layout_height="match_parent" />

</LinearLayout>

Edit: this is possible because I've imported the library project but I'm not using it as an imported .jar.