New UI-Java code dynamically add controls or xml layout, ui-javaxml

New UI-Java code dynamically add controls or xml layout, ui-javaxml

New UI-Java code dynamically add controls or xml la s

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This section introduces:

In the previous section, we learned pure Java code to load the layout. Now we have a little Dynamic Layout Foundation. In this section

We will explain how to dynamically Add a View control based on xml! And dynamic loading of XML

Layout!

Body of this section:

1. Add controls dynamically in Java code:

There are two ways to add components dynamically:SetContentView (R. layout. activity_main );

The following shows how to dynamically Add a Button to the interface.

The layout of the activity_main.xml file is as follows:

<RelativeLayout xmlns: android = "http://schemas.android.com/apk/res/android" xmlns: tools = "http://schemas.android.com/tools" android: id = "@ + id/RelativeLayout1" android: layout_width = "match_parent" android: layout_height = "match_parent" android: orientation = "vertical" tools: context = "com. jay. example. trendsinflateviewdemo. mainActivity "> <TextView android: id =" @ + id/txtTitle "android: layout_width =" match_parent "android: layout_height =" wrap_content "android: text = "I am the layout for loading xml files"/> </RelativeLayout>

First: setContentView () is not required ();

Package com. jay. example. trendsinflateviewdemo; import android. app. activity; import android. OS. bundle; import android. view. layoutInflater; import android. view. viewGroup. layoutParams; import android. widget. button; import android. widget. relativeLayout; public class MainActivity extends Activity {@ Overrideprotected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); Button btnOne = new Button (this); btnOne. setText ("I Am a dynamically added button"); RelativeLayout. layoutParams lp2 = new RelativeLayout. layoutParams (LayoutParams. WRAP_CONTENT, LayoutParams. WRAP_CONTENT); lp2.addRule (RelativeLayout. CENTER_IN_PARENT); LayoutInflater inflater = LayoutInflater. from (this); RelativeLayout rly = (RelativeLayout) inflater. inflate (R. layout. activity_main, null ). findViewById (R. id. relativeLayout1); rly. addView (btnOne, lp2); setContentView (rly );}}

Type 2: setContentView ();

Package com. jay. example. trendsinflateviewdemo; import android. app. activity; import android. OS. bundle; import android. view. viewGroup. layoutParams; import android. widget. button; import android. widget. relativeLayout; public class MainActivity extends Activity {@ Overrideprotected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. activity_main); Button btnOne = new Button (this); btnOne. setText ("I Am a dynamically added button"); RelativeLayout. layoutParams lp2 = new RelativeLayout. layoutParams (LayoutParams. WRAP_CONTENT, LayoutParams. WRAP_CONTENT); lp2.addRule (RelativeLayout. CENTER_IN_PARENT); RelativeLayout rly = (RelativeLayout) findViewById (R. id. relativeLayout1); rly. addView (btnOne, lp2 );}}

Analysis summary:

The code is very simple. After the Button is created, we create a LayoutParams object to set the size of the Button.

The addRule () method sets the Button position!

Method 1:PassInflate () method of LayoutInflateLoaded the activity_main layout, obtained the outer container, and then

AddView Add button to container, and setContentView ();

Method 2:Because we have loaded the layout through the setContetView () method, now we canFindViewById

Find this outer container, AddView, and setContentView!

In addition, the view node set by setContentView () is the root node of the entire XML file!

It is not difficult to add controls dynamically. If you read the previous article <pure Java loading layout>,

2. dynamically load xml layout with Java code

Next, let's change one. The xml file is loaded this time! Add xml files dynamically!

Write down the layout file first:

Activity_main.xml:

<RelativeLayout xmlns: android = "http://schemas.android.com/apk/res/android" xmlns: tools = "http://schemas.android.com/tools" android: id = "@ + id/RelativeLayout1" android: layout_width = "match_parent" android: layout_height = "match_parent" android: orientation = "vertical" tools: context = "com. jay. example. trendsinflateviewdemo. mainActivity "> <Button android: id =" @ + id/btnLoad "android: layout_width =" match_parent "android: layout_height =" wrap_content "android: text = "dynamic loading layout"/> </RelativeLayout>

Dynamically Loaded xml file inflate. xml:

<? 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: gravity = "center" android: orientation = "vertical" android: id = "@ + id/ly_inflate"> <TextView android: layout_width = "wrap_content" android: layout_height = "wrap_content" android: text = "I'm a Java code loading layout"/> <Button android: layout_width = "wrap_content" android: layout_height = "wrap_content" android: text = "I am a small button in the layout"/> </LinearLayout>

Next we will go to MainActivity. java:

Package com. jay. example. trendsinflateviewdemo; import android. app. activity; import android. OS. bundle; import android. view. layoutInflater; import android. view. view; import android. view. view. onClickListener; import android. view. viewGroup. layoutParams; import android. widget. button; import android. widget. linearLayout; import android. widget. relativeLayout; public class MainActivity extends Activity {@ Overrideprotected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. activity_main); // obtain the LayoutInflater object; final LayoutInflater inflater = LayoutInflater. from (this); // obtain the external container object final RelativeLayout rly = (RelativeLayout) findViewById (R. id. relativeLayout1); Button btnLoad = (Button) findViewById (R. id. btnLoad); btnLoad. setOnClickListener (new OnClickListener () {@ Overridepublic void onClick (View v) {// load the layout object LinearLayout ly = (LinearLayout) inflater. inflate (R. layout. inflate_ly, null, false ). findViewById (R. id. ly_inflate); // sets the size and position of the loaded layout. layoutParams lp = new RelativeLayout. layoutParams (LayoutParams. WRAP_CONTENT, LayoutParams. WRAP_CONTENT); lp. addRule (RelativeLayout. CENTER_IN_PARENT); rly. addView (ly, lp );}});}}

Run:

Next we will analyze the Code:

① Get the container object:

Final RelativeLayout rly = (RelativeLayout) findViewById (R. id. RelativeLayout1 );

② Obtain the Inflater object, load the xml of the added layout, and find the root node of the outermost layer through findViewById

FInal LayoutInflater inflater = LayoutInflater. from (this );

LinearLayout ly = (LinearLayout) inflater. inflate (
R. layout. inflate_ly, null, false). findViewById (
R. id. ly_inflate );

③ Set the size and location information for the container:

RelativeLayout. LayoutParams lp = new RelativeLayout. LayoutParams (
LayoutParams. WRAP_CONTENT, LayoutParams. WRAP_CONTENT );
Lp. addRule (RelativeLayout. CENTER_IN_PARENT );

④ Add to outer container:

Rly. addView (ly, lp );

Now, let's talk about how to dynamically add controls or XML content through Java code!

In addition, after addView (), when this View does not need to be used, you can use RemoveView ()

This View is removed!