我有2个活动,1个叫做MainActivity,另一个叫做Circle。当我单击MainActivity上的按钮以启动第二个按钮时,我想要一个进度条加载屏幕。这是我目前的代码,但它只是导致应用程序崩溃。
public class LoadingScreenActivity extends Activity
{
//A ProgressDialog object
private ProgressDialog progressDialog;
/** 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>
{
//Before running code in the separate thread
@Override
protected void onPreExecute()
{
//Create a new progress dialog
progressDialog = new ProgressDialog(LoadingScreenActivity.this);
//Set the progress dialog to display a horizontal progress bar
progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
//Set the dialog title to 'Loading...'
progressDialog.setTitle("Loading...");
//Set the dialog message to 'Loading application View, please wait...'
progressDialog.setMessage("Loading application View, please wait...");
//This dialog can't be canceled by pressing the back key
progressDialog.setCancelable(false);
//This dialog isn't indeterminate
progressDialog.setIndeterminate(false);
//The maximum number of items is 100
progressDialog.setMax(100);
//Set the current progress to zero
progressDialog.setProgress(0);
//Display the progress dialog
progressDialog.show();
}
//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 progress
@Override
protected void onProgressUpdate(Integer... values)
{
//set the current progress of the progress dialog
progressDialog.setProgress(values[0]);
}
//after executing the code in the thread
@Override
protected void onPostExecute(Void result)
{
//close the progress dialog
progressDialog.dismiss();
//initialize the View
setContentView(R.layout.content_circle);
}
}
}
首先为ProgressDialog创建一个公共的类实用程序来重用代码
public class Utility {
public static ProgressDialog getProgressDialog(Context context) {
ProgressDialog progressDialog = new ProgressDialog(context,
R.style.TransparentDialog);
progressDialog.setCancelable(false);
progressDialog
.setProgressStyle(android.R.style.Widget_ProgressBar_Small);
progressDialog.setProgress(0);
return progressDialog;
}
}
然后在您的活动或片段中使用Above类。但是你必须使用Intent来进行下一个活动。您无法直接设置下一个活动布局
public class LoadingScreenActivity extends Activity
{
//A ProgressDialog object
protected ProgressDialog dialog;
/** 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>
{
//Before running code in the separate thread
@Override
protected void onPreExecute()
{
super.onPreExecute();
dialog = Utility.getProgressDialog(context);
dialog.setCanceledOnTouchOutside(false);
dialog.setCancelable(false);
if (dialog != null) {
dialog.show();
}
}
//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;
}
//after executing the code in the thread
@Override
protected void onPostExecute(Void result)
{
//close the progress dialog
dialog.dismiss();
// use intent here to go next activity
Intent i = new Intent(this,SecondActivity.class);
startIntent(i);
}
}
您可以在默认情况下可见的第二个活动XML中添加一些默认视图,如progressbar。当您加载数据或其他任何内容时,将其设置为view.GONE
。好的图书馆是这样的:
https://github.com/81813780/AVLoadingIndicatorView
在你的second_activity.xml中使用:
<com.wang.avi.AVLoadingIndicatorView
android:layout_gravity="center"
android:id="@+id/avloadingIndicatorView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="visible"
app:indicatorName="BallPulse"
app:indicatorColor="@color/myPrimaryColor"/>
然后在你的活动onCreate()方法中:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
loader= (AVLoadingIndicatorView) findViewById(R.id.avloadingIndicatorView);
}
最后当你完成加载时,只需使用:
loader.setVisibility(View.GONE);