Java 按下后退按钮时,计时器未关闭。按钮按下时强制关闭错误
好的,你们都是超级java/android大师。我知道你会看着这个笑,但我真的需要帮助。我是一个超级新手,读过谷歌的每一篇开发文档(还有更多),只是不能理解这个概念。通过查看工作代码可以学到更多,而不是参考我已经读过但显然不理解的内容,所以如果有人能帮助我,那就太好了 主要活动Java 按下后退按钮时,计时器未关闭。按钮按下时强制关闭错误,java,android,timer,onresume,onpause,Java,Android,Timer,Onresume,Onpause,好的,你们都是超级java/android大师。我知道你会看着这个笑,但我真的需要帮助。我是一个超级新手,读过谷歌的每一篇开发文档(还有更多),只是不能理解这个概念。通过查看工作代码可以学到更多,而不是参考我已经读过但显然不理解的内容,所以如果有人能帮助我,那就太好了 主要活动 import java.util.Timer; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecuto
import java.util.Timer;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.webkit.WebView;
public class Quotes extends Activity implements OnClickListener {
ProgressDialog dialog;
private WebView webview;
private Timer timer;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
WebView adsview = (WebView) findViewById(R.id.ads);
adsview.getSettings().setJavaScriptEnabled(true);
adsview.loadUrl("http://www.dgdevelco.com/quotes/androidad.html");
SharedPreferences SP = PreferenceManager.getDefaultSharedPreferences(getBaseContext());
String q = SP.getString("appViewType","http://www.dgdevelco.com/quotes/quotesandroidtxt.html");
String c = SP.getString("appRefreshRate","20");
webview = (WebView) findViewById(R.id.scroll);
webview.getSettings().setJavaScriptEnabled(true);
webview.setWebViewClient(new QuotesWebView(this));
webview.loadUrl(q);
ScheduledExecutorService timer = Executors.newSingleThreadScheduledExecutor();
timer.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
webview.reload();
}
}, 10, Long.parseLong(c),TimeUnit.SECONDS);
findViewById(R.id.refresh).setOnClickListener(this);
}
@Override
public void onPause(){
timer.cancel();
super.onPause();
}
@Override
public void onResume(){
webview.reload();
super.onResume();
}
public void onClick(View v){
switch(v.getId()){
case R.id.refresh:
webview.reload();
break;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
MenuItem about = menu.getItem(0);
about.setIntent(new Intent(this, About.class));
MenuItem preferences = menu.getItem(1);
preferences.setIntent(new Intent(this, Preferences.class));
return true;
}
}
CatLog
07-05 17:28:51.001: DEBUG/AndroidRuntime(11446): Shutting down VM
07-05 17:28:51.001: WARN/dalvikvm(11446): threadid=1: thread exiting with uncaught exception (group=0x40018560)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): FATAL EXCEPTION: main
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): java.lang.RuntimeException: Unable to pause activity {com.dge.quotes/com.dge.quotes.Quotes}: java.lang.NullPointerException
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at android.app.ActivityThread.performPauseActivity(ActivityThread.java:2477)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at android.app.ActivityThread.performPauseActivity(ActivityThread.java:2424)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at android.app.ActivityThread.handlePauseActivity(ActivityThread.java:2404)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at android.app.ActivityThread.access$1700(ActivityThread.java:124)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:979)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at android.os.Handler.dispatchMessage(Handler.java:99)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at android.os.Looper.loop(Looper.java:123)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at android.app.ActivityThread.main(ActivityThread.java:3806)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at java.lang.reflect.Method.invokeNative(Native Method)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at java.lang.reflect.Method.invoke(Method.java:507)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at dalvik.system.NativeStart.main(Native Method)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): Caused by: java.lang.NullPointerException
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at com.dge.quotes.Quotes.onPause(Quotes.java:72)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at android.app.Activity.performPause(Activity.java:3901)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at android.app.Instrumentation.callActivityOnPause(Instrumentation.java:1191)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): at android.app.ActivityThread.performPauseActivity(ActivityThread.java:2459)
07-05 17:28:51.017: ERROR/AndroidRuntime(11446): ... 12 more
07-05 17:28:51.509: WARN/ActivityManager(1319): Activity pause timeout for HistoryRecord{40ba7e20 com.dge.quotes/.Quotes}
我们将非常感谢您的任何帮助
在这一点上,我感觉自己像一个完全疯狂的女人,她真的需要完成这个项目,这样我的生活才能向前发展。如果有人对此有答案,我将不胜感激。您可以尝试在活动中拦截onBackPressed,然后执行计时器。取消()。差不多
@Override
public void onBackPressed() {
timer.cancel();
}
您可以尝试在活动中拦截onBackPressed,然后执行计时器。取消()。差不多
@Override
public void onBackPressed() {
timer.cancel();
}
onStop()是放置timer.cancel()的更可靠的位置(如果您想涵盖几乎所有情况,如结尾所述的情况,可以同时放置这两个位置)
onPause()并不是在所有情况下都被调用,它是在onResume()很可能发生时使用的,例如当您继续执行另一个活动然后返回时。注意图中的缩进。当按下后退按钮时,可能不会调用它
编辑1:这是预编辑答案,因此可能不包括强制关闭问题
编辑2:
@Override
public void onStop(){
super.onStop();
try {
timer.cancel();
} catch (Exception ex) {
Log.e("MY APP ERROR", ex.getMessage());
}
}
在这些生命周期方法中,我总是把调用super放在首位。我不确定这是否有区别。您可能还需要设置try/catch语句,特别是如果您选择在onStop()和onPause()中都包含timer.cancel()
编辑3:
准备承认失败。我对ScheduledExecutorService的怪癖不太熟悉,既然你表示愿意重写,下面是我如何在我的应用程序中完成同样的事情的。Handler是一个特定于Android的实现,所以也许这就是为什么我没有遇到与您相同的问题
Handler timer;
Runnable runner;
@Override
onCreate(...) {
...
//EDIT 4: (reading time from preferences)
SharedPreferences SP = PreferenceManager.getDefaultSharedPreferences(getBaseContext());
final int c = Integer.parseInt(SP.getString("appRefreshRate","20"));
...
runner = new Runnable() {
@Override
public void run() {
timer.postDelayed(runner, c * 1000);
webview.reload();
}
};
timer = new Handler();
timer.postDelayed(runner, c * 1000);
...
}
@Override
public void onPause(){
super.onPause();
try {
timer.removeCallbacks(runner);
} catch (Exception ex) {
Log.e("MY APP ERROR", ex.getMessage());
}
}
@Override
public void onStop(){
super.onStop();
try {
timer.removeCallbacks(runner);
} catch (Exception ex) {
Log.e("MY APP ERROR", ex.getMessage());
}
}
onStop()是放置timer.cancel()的更可靠的位置(如果您想涵盖几乎所有情况,如结尾所述的情况,可以同时放置这两个位置)
onPause()并不是在所有情况下都被调用,它是在onResume()很可能发生时使用的,例如当您继续执行另一个活动然后返回时。注意图中的缩进。当按下后退按钮时,可能不会调用它
编辑1:这是预编辑答案,因此可能不包括强制关闭问题
编辑2:
@Override
public void onStop(){
super.onStop();
try {
timer.cancel();
} catch (Exception ex) {
Log.e("MY APP ERROR", ex.getMessage());
}
}
在这些生命周期方法中,我总是把调用super放在首位。我不确定这是否有区别。您可能还需要设置try/catch语句,特别是如果您选择在onStop()和onPause()中都包含timer.cancel()
编辑3:
准备承认失败。我对ScheduledExecutorService的怪癖不太熟悉,既然你表示愿意重写,下面是我如何在我的应用程序中完成同样的事情的。Handler是一个特定于Android的实现,所以也许这就是为什么我没有遇到与您相同的问题
Handler timer;
Runnable runner;
@Override
onCreate(...) {
...
//EDIT 4: (reading time from preferences)
SharedPreferences SP = PreferenceManager.getDefaultSharedPreferences(getBaseContext());
final int c = Integer.parseInt(SP.getString("appRefreshRate","20"));
...
runner = new Runnable() {
@Override
public void run() {
timer.postDelayed(runner, c * 1000);
webview.reload();
}
};
timer = new Handler();
timer.postDelayed(runner, c * 1000);
...
}
@Override
public void onPause(){
super.onPause();
try {
timer.removeCallbacks(runner);
} catch (Exception ex) {
Log.e("MY APP ERROR", ex.getMessage());
}
}
@Override
public void onStop(){
super.onStop();
try {
timer.removeCallbacks(runner);
} catch (Exception ex) {
Log.e("MY APP ERROR", ex.getMessage());
}
}
活动中有一个名为Timer的专用计时器,但由于活动中有另一个名为Timer的计时器,因此该计时器似乎尚未初始化。在webview下定义的专用计时器为null,因此在调用onPause时会得到nullpointexception 如果从onCreate()中删除该类,则可能需要将计时器定义为singlethreadscheduledexecutor
timer = Executors.newSingleThreadScheduledExecutor();
timer.scheduleAtFixedRate(new Runnable() {
您的代码和建议答案:
import java.util.Timer;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.webkit.WebView;
public class Quotes extends Activity implements OnClickListener {
ProgressDialog dialog;
private WebView webview;
private Timer timer;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
WebView adsview = (WebView) findViewById(R.id.ads);
adsview.getSettings().setJavaScriptEnabled(true);
adsview.loadUrl("http://www.dgdevelco.com/quotes/androidad.html");
SharedPreferences SP = PreferenceManager.getDefaultSharedPreferences(getBaseContext());
String q = SP.getString("appViewType","http://www.dgdevelco.com/quotes/quotesandroidtxt.html");
String c = SP.getString("appRefreshRate","20");
webview = (WebView) findViewById(R.id.scroll);
webview.getSettings().setJavaScriptEnabled(true);
webview.setWebViewClient(new QuotesWebView(this));
webview.loadUrl(q);
timer = Executors.newSingleThreadScheduledExecutor();
timer.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
webview.reload();
}
}, 10, Long.parseLong(c),TimeUnit.SECONDS);
findViewById(R.id.refresh).setOnClickListener(this);
}
@Override
public void onPause(){
timer.cancel();
super.onPause();
}
@Override
public void onResume(){
webview.reload();
super.onResume();
}
public void onClick(View v){
switch(v.getId()){
case R.id.refresh:
webview.reload();
break;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
MenuItem about = menu.getItem(0);
about.setIntent(new Intent(this, About.class));
MenuItem preferences = menu.getItem(1);
preferences.setIntent(new Intent(this, Preferences.class));
return true;
}
}
活动中有一个名为Timer的专用计时器,但由于活动中有另一个名为Timer的计时器,因此该计时器似乎尚未初始化。在webview下定义的专用计时器为null,因此在调用onPause时会得到nullpointexception 如果从onCreate()中删除该类,则可能需要将计时器定义为singlethreadscheduledexecutor
timer = Executors.newSingleThreadScheduledExecutor();
timer.scheduleAtFixedRate(new Runnable() {
您的代码和建议答案:
import java.util.Timer;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.webkit.WebView;
public class Quotes extends Activity implements OnClickListener {
ProgressDialog dialog;
private WebView webview;
private Timer timer;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
WebView adsview = (WebView) findViewById(R.id.ads);
adsview.getSettings().setJavaScriptEnabled(true);
adsview.loadUrl("http://www.dgdevelco.com/quotes/androidad.html");
SharedPreferences SP = PreferenceManager.getDefaultSharedPreferences(getBaseContext());
String q = SP.getString("appViewType","http://www.dgdevelco.com/quotes/quotesandroidtxt.html");
String c = SP.getString("appRefreshRate","20");
webview = (WebView) findViewById(R.id.scroll);
webview.getSettings().setJavaScriptEnabled(true);
webview.setWebViewClient(new QuotesWebView(this));
webview.loadUrl(q);
timer = Executors.newSingleThreadScheduledExecutor();
timer.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
webview.reload();
}
}, 10, Long.parseLong(c),TimeUnit.SECONDS);
findViewById(R.id.refresh).setOnClickListener(this);
}
@Override
public void onPause(){
timer.cancel();
super.onPause();
}
@Override
public void onResume(){
webview.reload();
super.onResume();
}
public void onClick(View v){
switch(v.getId()){
case R.id.refresh:
webview.reload();
break;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
MenuItem about = menu.getItem(0);
about.setIntent(new Intent(this, About.class));
MenuItem preferences = menu.getItem(1);
preferences.setIntent(new Intent(this, Preferences.class));
return true;
}
}
你按下按钮时出现了什么错误?对不起,在onPause中强制关闭,我假设如果它成功了,onResume也会有问题。请添加stacktrace(实际上,我希望每次定时器启动时它都会崩溃)@mibollma如果你认为它会更好的话,我完全可以重写整个过程。-->你按下按钮时出现了什么错误?很抱歉,在onPause中强制关闭,我假设如果它成功了,onResume也会有问题。请添加stacktrace(实际上,我希望每次定时器启动时它都会崩溃)@mibollma如果你认为它会更好的话,我完全可以重写整个代码。-->那代码会是什么样子?我试过了,但没有成功,但可能是做错了。“不工作”是指计时器仍在运行还是强制关闭?07-05 17:51:51.580:ERROR/AndroidRuntime(11844):java.lang.RuntimeException:无法停止活动{com.dge.quotes/com.dge.quotes.quotes}:java.lang.NullPointerException可能有效,但如何调用字符串c(来自首选项的用户输入)进入计时器?编辑以演示用户偏好输入,但@david olsson看到了我在阅读您的代码时错过的上千次。该代码是什么样子的?我尝试过,但没有成功,但可能是做错了。“不工作”是指计时器仍在运行还是强制关闭?07-05 17:51:51.580:ERROR/AndroidRuntime(11844):java.lang.RuntimeException:无法停止活动{com.dge.quotes/com.dge.quotes.quotes}:java.lang.nullpointerException可能会工作,但我如何将字符串c(来自首选项的用户输入)调用到计时器中?编辑以演示用户首选项输入,但@david olsson看到了w