[英]Progress dialog keeps on displaying in android studio
我是android开发的新手。 我正在为我的应用程序使用android studio
。 我创建了一个DB
,然后在Yii中创建了一个web service
,在ARC
上对其进行了测试并使用GET
方法,它完美地显示了结果。 从那以后,我创建了一个app
中,我想使用的web service
和使用它的get方法来显示结果。
下面是我的数据库表结构
场景是,当用户在应用程序中输入id
并点击“提交”按钮时,它应该显示相应的username
。 为此,请参见以下代码
表现
<uses-permission android:name="android.permission.INTERNET"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
MainActivity.java
public class MainActivity extends AppCompatActivity {
String URLGET = "http://my_ip:8000/app/web/users/";
String result = "";
TextView tv;
public static final String LOG_TAG = MainActivity.class.getSimpleName();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button button = (Button) findViewById(R.id.btn_Submit);
button.setOnClickListener(new Button.OnClickListener() {
@Override
public void onClick(View v) {
String reqURL = URLGET;
new RestOperation().execute(reqURL);
//callWebService(query);
}
});
}
public class RestOperation extends AsyncTask<String, Void, Void> {
final HttpClient httpClient = new DefaultHttpClient();
String content;
String error;
ProgressDialog progressDialog = new ProgressDialog(MainActivity.this);
String data = "";
TextView getData = (TextView) findViewById(R.id.getData);
EditText userInput = (EditText) findViewById(R.id.EnterId);
@Override
protected void onPreExecute() {
super.onPreExecute();
progressDialog.setTitle("Please Wait...");
progressDialog.show();
try {
data += "&" + URLEncoder.encode("data", "UTF-8") + "-" + userInput.getText();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
@Override
protected Void doInBackground(String... params) {
BufferedReader br = null;
URL url = null;
try {
url = new URL(params[0]);
URLConnection connection = url.openConnection();
connection.setDoOutput(true);
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(connection.getOutputStream());
outputStreamWriter.write(data);
outputStreamWriter.flush();
br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = br.readLine()) != null) {
sb.append(line);
sb.append(System.getProperty("line.separator"));
}
content = sb.toString();
} catch (MalformedURLException e) {
error = e.getMessage();
e.printStackTrace();
} catch (IOException e) {
error = e.getMessage();
e.printStackTrace();
} finally {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
progressDialog.dismiss();
if (error != null) {
getData.setText("Error" + error);
} else {
getData.setText(content);
}
}
}
}
但是,当我运行该应用程序时,输入任何给定的ID并执行提交。 进度条显示了很长一段时间,然后应用程序崩溃,出现以下错误。
FATAL EXCEPTION: AsyncTask #1
Process: com.example.accurat.webservice, PID: 642
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:304)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void java.io.BufferedReader.close()' on a null object reference
at com.example.accurat.webservice.MainActivity$RestOperation.doInBackground(MainActivity.java:141)
at com.example.accurat.webservice.MainActivity$RestOperation.doInBackground(MainActivity.java:72)
at android.os.AsyncTask$2.call(AsyncTask.java:292)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
02-07 15:57:42.929 642-642/com.example.accurat.webservice E/WindowManager: android.view.WindowLeaked: Activity com.example.accurat.webservice.MainActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{3f2c8572 V.E..... R......D 0,0-729,322} that was originally added here
at android.view.ViewRootImpl.<init>(ViewRootImpl.java:363)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:271)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:85)
at android.app.Dialog.show(Dialog.java:298)
at com.example.accurat.webservice.MainActivity$RestOperation.onPreExecute(MainActivity.java:90)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:591)
at android.os.AsyncTask.execute(AsyncTask.java:539)
at com.example.accurat.webservice.MainActivity$1.onClick(MainActivity.java:65)
at android.view.View.performClick(View.java:4780)
at android.view.View$PerformClick.run(View.java:19866)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
我在Google上搜索了许多文章,但是找不到正确的答案,尽管我尝试实现它们,但仍然没有结果。
以下是我的搜索结果。
更新1
通过使用Ben
和X3Btel
建议,我的应用程序停止崩溃,但在模拟器上显示以下错误
然后,我再次将我的ip
替换为localhost
但仍然看到相同的错误。
我正在模拟器上测试我的应用程序,因此我将ip
地址放在url中。
我几乎整天都坚持不懈。 任何帮助,将不胜感激。
您收到一个nullpointer异常。
如果在初始化读取器之前发生异常,则将导致此错误,因为br.close()被放置在finally块中。 优良作法是在最终关闭资源之前始终检查null 。
在finally块中尝试这个
if(br!= null)
br.close();
祝好运
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