我想在应用程序启动之前显示类加载。
所以，我有类在打开我的应用程序之前显示加载图像。
但我的问题是，我有 2 节课，src第一节课main.java，第二节课LoadingScreenActivity.java。
我如何打开课程LoadingScreenActivity.java然后当我的应用程序加载成功时打开主课程main.java。
这是 LoadingScreenActivity 类：-
public class LoadingScreenActivity extends Activity
{
//creates a ViewSwitcher object, to switch between Views
private ViewSwitcher viewSwitcher;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
//Initialize a LoadViewTask object and call the execute() method
new LoadViewTask().execute();
}
//To use the AsyncTask, it must be subclassed
private class LoadViewTask extends AsyncTask<Void, Integer, Void>
{
//A TextView object and a ProgressBar object
private TextView tv_progress;
private ProgressBar pb_progressBar;
//Before running code in the separate thread
@Override
protected void onPreExecute()
{
//Initialize the ViewSwitcher object
viewSwitcher = new ViewSwitcher(LoadingScreenActivity.this);
/* Initialize the loading screen with data from the 'loadingscreen.xml' layout xml file.
* Add the initialized View to the viewSwitcher.*/
viewSwitcher.addView(ViewSwitcher.inflate(LoadingScreenActivity.this, R.layout.activity_main, null));
//Initialize the TextView and ProgressBar instances - IMPORTANT: call findViewById() from viewSwitcher.
tv_progress = (TextView) viewSwitcher.findViewById(R.id.tv_progress);
pb_progressBar = (ProgressBar) viewSwitcher.findViewById(R.id.pb_progressbar);
//Sets the maximum value of the progress bar to 100
pb_progressBar.setMax(100);
//Set ViewSwitcher instance as the current View.
setContentView(viewSwitcher);
}
//The code to be executed in a background thread.
@Override
protected Void doInBackground(Void... params)
{
/* This is just a code that delays the thread execution 4 times,
* during 850 milliseconds and updates the current progress. This
* is where the code that is going to be executed on a background
* thread must be placed.
*/
try
{
//Get the current thread's token
synchronized (this)
{
//Initialize an integer (that will act as a counter) to zero
int counter = 0;
//While the counter is smaller than four
while(counter <= 4)
{
//Wait 850 milliseconds
this.wait(850);
//Increment the counter
counter++;
//Set the current progress.
//This value is going to be passed to the onProgressUpdate() method.
publishProgress(counter*25);
}
}
}
catch (InterruptedException e)
{
e.printStackTrace();
}
return null;
}
//Update the TextView and the progress at progress bar
@Override
protected void onProgressUpdate(Integer... values)
{
//Update the progress at the UI if progress value is smaller than 100
if(values[0] <= 100)
{
tv_progress.setText("Progress: " + Integer.toString(values[0]) + "%");
pb_progressBar.setProgress(values[0]);
}
}
//After executing the code in the thread
@Override
protected void onPostExecute(Void result)
{
/* Initialize the application's main interface from the 'main.xml' layout xml file.
* Add the initialized View to the viewSwitcher.*/
viewSwitcher.addView(ViewSwitcher.inflate(LoadingScreenActivity.this, R.layout.activity_main, null));
//Switch the Views
viewSwitcher.showNext();
}
}
//Override the default back key behavior
@Override
public void onBackPressed()
{
//Emulate the progressDialog.setCancelable(false) behavior
//If the first view is being shown
if(viewSwitcher.getDisplayedChild() == 0)
{
//Do nothing
return;
}
else
{
//Finishes the current Activity
super.onBackPressed();
}
}
}
这是主要课程：-
public class MainActivity extends Activity implements OnClickListener{
public MediaPlayer mp;
boolean isPrepared = false;
Button PlayBtn;
Button PauseBtn;
Button StopBtn;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mp = new MediaPlayer();
PlayBtn = (Button)findViewById(R.id.btnPlay);
PlayBtn .setOnClickListener(this);
PauseBtn = (Button)findViewById(R.id.btnPause);
PauseBtn .setOnClickListener(this);
StopBtn = (Button)findViewById(R.id.btnStop);
StopBtn .setOnClickListener(this);
}
@Override
public void onClick(View v){
if(v == PlayBtn){
startradio(v);
}
else if(v == PauseBtn){
pauseradio(v);
}
else if(v == StopBtn){
stopradio(v);
}
}
public void onCompletion(MediaPlayer mediaPlayer) {
synchronized(this){
isPrepared = false;
}
}
protected void onResume (){
super.onResume();
try {
mp.setDataSource("http://radio.arabhosters.com:8015/");
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SecurityException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
try {
mp.prepare();
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} //also consider mp.prepareAsync().
// defult start stream when start App.
mp.start();
}
// method for play stream after stop it.
public void startradio(View v) {
try{
if(mp.isPlaying()){
return;
}
mp.start();
} catch(IllegalStateException ex){
ex.printStackTrace();
}
}
// method for pause stream.
public void pauseradio(View v) {
mp.pause();
}
public boolean isPlaying() {
return mp.isPlaying();
}
public boolean isLooping() {
return mp.isLooping();
}
public void setLooping(boolean isLooping) {
mp.setLooping(isLooping);
}
public void setVolume(float volumeLeft, float volumeRight) {
mp.setVolume(volumeLeft, volumeRight);
}
// method for stop stream.
public void stopradio(View v) {
if(mp.isPlaying()){
mp.stop();
}
mp.release();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
编辑 ：-
清单.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.kam"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.kam.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>