title: Set child layout width programmatically In ANDROID?
body: <p>In my Code I have a XML file having multiple child layouts. Aand I just want to set one of these child layout's width programmatically according to device's screen width.
  till now I had tried Layout params, setparam, and other methods but it shows null pointer exception on getting layout id.</p>
  
  <p>my parent layout is a Relative Layout,
  and 1st Child Layout is a Linear Layout("for this layout I need to change width")</p>
  
  <pre><code>&lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:id="@+id/parentlayout"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"&gt;
  
      &lt;LinearLayout
          android:id="@+id/childlayout"
          android:layout_width="250dip"
          android:layout_height="fill_parent"
          android:orientation="vertical" 
          android:background="#153746"&gt;
          &lt;LinearLayout
              android:layout_width="fill_parent"
              android:layout_height="wrap_content"
              android:orientation="vertical"
              android:background="@drawable/sub_title"
              android:gravity="center_vertical" &gt;
              &lt;TextView
                  android:id="@+id/menu_header_label"
                  android:layout_width="wrap_content"
                  android:layout_height="wrap_content"
                  android:textStyle="bold"
                  android:text="asd"
                  android:textColor="#ffffff"
                  android:layout_marginLeft="10dip" /&gt;
  
              &lt;ImageView
                  android:id="@+id/menu_header"
                  android:layout_width="wrap_content"
                  android:layout_height="wrap_content"
                  android:layout_gravity="center_horizontal" /&gt;
          &lt;/LinearLayout&gt;
          &lt;ListView
              android:id="@+id/menu_listview"
              android:layout_width="fill_parent"
              android:layout_height="wrap_content"
              android:divider="@android:color/darker_gray"
              android:dividerHeight="1dip"
              android:scrollingCache="false" /&gt;
      &lt;/LinearLayout&gt;
  
      &lt;FrameLayout
          android:id="@+id/overlay"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent" &gt;
      &lt;/FrameLayout&gt;
  
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>Java Code:-</p>
  
  <pre><code>     public class SlideMenu extends LinearLayout {
  
      // keys for saving/restoring instance state
      public final static String KEY_MENUSHOWN = "menuWasShown";
      private final static String KEY_STATUSBARHEIGHT = "statusBarHeight";
      private final static String KEY_SUPERSTATE = "superState";
  
  //  Display display = ((WindowManager) getWindowToken()).getDefaultDisplay(); 
  //  int width = display.getWidth();  // deprecated
  //  int height = display.getHeight();  // deprecated
  //  float layWidth = (width*70)/100;
  //  
  ////    LinearLayout view= (LinearLayout)findViewById(R.id.childlayout);
  ////    LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) view.getLayoutParams();
  ////    params.width = 130;
  ////    view.setLayoutParams(params);
  //  view.setLayoutParams(new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT, theSizeIWant));
  
      public static class SlideMenuItem {
          public int id;
          public Drawable icon;
          public String label;
      } 
  </code></pre>
  
  <p>here is my code snippet and i comment the part what i tried so far and get any fine result..``</p>