Android Layouts

There are two ways to create Layout.

1. Layouts in XML
2. Layouts in Code

1. Layouts in XML

Example: main.xml(Layout file)

     <?xml version=”1.0” encoding=”utf-8”?>
     <LinearLayout   xmlns:android=”http://schemas.android.com/apk/res/android”
                                android:orientation=”vertical”
                                android:layout_width=”fill_parent”
                                android:layout_height=”fill_parent” >
     <TextView   android:id=”@+id/mytxt”
                          android:layout_width=”fill_parent”
                          android:layout_height=”wrap_content”
                          android:text=”@string/Write here..” />
     </LinearLayout>

• It's a preferred way of implementing your user interfaces (UIs) or defining your UI in XML.
• As it decouples your application logic from your UI design.
• Keeping the visual design decoupled from the application code, helps keep the code concise.
• To get access to the UI elements we have to add identifier(id) attributes to them in the XML definition.

                                android:id=”@+id/mytxt”

• The above line generates an id named "mytxt" for TextView,which are stored in /gen/packageName/R.java of your poject hierarchy.

       In R.java file, following line generates:
     public final class R {
          public static final class id {
                        public static final int mytxt=0x7f050044;
                                    }
                         }

2. Layouts in Code

     public class MainActivity extends Activity {
          public void onCreate(Bundle savedInstanceState) {
               super.onCreate(savedInstanceState);

              LinearLayout ll = new LinearLayout(this);
              ll.setOrientation(LinearLayout.VERTICAL);

              TextView myTxtView = new TextView(this);
              EditText myEdtText = new EditText(this);
              myTxtView.setText(“Enter Text”);
              myEdtText.setText(“Write Text Here!”);

              int lHeight = LinearLayout.LayoutParams.MATCH_PARENT;
              int lWidth = LinearLayout.LayoutParams.WRAP_CONTENT;

              ll.addView(myTxtView, new LinearLayout.LayoutParams(lHeight, lWidth));
              ll.addView(myEdtText, new LinearLayout.LayoutParams(lHeight, lWidth));
              setContentView(ll);
 }   }

It's not a preferred way of implementing your user interfaces (UIs).