您的位置：首页 > 移动开发

android-UI design(first app)

2015-12-27 20:11 393 查看

The graphical user interface for an Android app is built using a hierarchy of

View

and

ViewGroup

objects.

View

objects
are usually UI widgets such as buttons or text
fields.

ViewGroup

objects
are invisible view containers that define how the child views are laid out, such as in a grid or a vertical list.

Layouts are subclasses of the

ViewGroup

.
In this exercise, you'll work with a

LinearLayout

.

> Run Your App: adb
install -r app/build/outputs/apk/app-debug.apk

/** Called when the user clicks the Send button */
public void sendMessage(View view) {
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}

public class DisplayMessageActivity extends AppCompatActivity {

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

if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle app bar item clicks here. The app bar
// automatically handles clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}

/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {

public PlaceholderFragment() { }

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_display_message,
container, false);
return rootView;
}
}
}

Note: If you
are using an IDE other than Android Studio, your project does not contain the

activity_display_message

layout that's requested by

setContentView()

.
That's OK because you will update this method later and won't be using that layout.

>In your manifest file,

AndroidManifest.xml

,
within the

Application

element, add the

<activity>

element
for your

DisplayMessageActivity

class, as follows:

<application ... >
...
<activity
android:name="com.mycompany.myfirstapp.DisplayMessageActivity"
android:label="@string/title_activity_display_message"
android:parentActivityName="com.mycompany.myfirstapp.MyActivity" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.mycompany.myfirstapp.MyActivity" />
</activity>
</application>

The system uses this value to implement default navigation behaviors, such as Up
navigationon Android 4.1 (API level 16) and higher. You can provide the same navigation behaviors for older versions of Android by using the Support
Library and adding the

<meta-data>

element
as shown here.

> The complete

onCreate()

method
for

DisplayMessageActivity

now looks like this:

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_message);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);

FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null)
.show();
}
});
getSupportActionBar().setDisplayHomeAsUpEnabled(true);

Intent intent = getIntent();
String message = intent.getStringExtra(MyActivity.EXTRA_MESSAGE);
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);

RelativeLayout layout = (RelativeLayout) findViewById(R.id.content);
layout.addView(textView);

内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理

标签：

相关文章推荐

新的分享

章节导航