Android Adapterview类中的Asynctask
我正在尝试更改listview项目的字体。如果没有AsyncTasc,则需要花费太多时间。将AsyncTask活动与该listview一起使用会在实例应用程序崩溃后快速出现。我知道我不能直接从AsyncTasc更改UI。我可以使用什么?提前谢谢Android Adapterview类中的Asynctask,android,android-listview,android-asynctask,Android,Android Listview,Android Asynctask,我正在尝试更改listview项目的字体。如果没有AsyncTasc,则需要花费太多时间。将AsyncTask活动与该listview一起使用会在实例应用程序崩溃后快速出现。我知道我不能直接从AsyncTasc更改UI。我可以使用什么?提前谢谢 import ru.ayratbadykov.feedhandler.FEED; import ru.ayratbadykov.feedhandler.RssMessage; import android.content.Context; import
import ru.ayratbadykov.feedhandler.FEED;
import ru.ayratbadykov.feedhandler.RssMessage;
import android.content.Context;
import android.graphics.Typeface;
import android.os.AsyncTask;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
public class CustomAdapter extends BaseAdapter {
private FEED _data;
Context _c;
CustomAdapter(FEED data, Context c) {
_data = data;
_c = c;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
Log.w("here","here");
View v = convertView;
if (v == null) {
LayoutInflater vi = (LayoutInflater) _c
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.customadapter, null);
}
TextView fromView = (TextView) v.findViewById(R.id.textView1);
TextView subView = (TextView) v.findViewById(R.id.textView2);
TextView View = (TextView) v.findViewById(R.id.textView3);
RssMessage msg = _data.getMessages().get(position);
new Font().execute(fromView,subView,View);
fromView.setText(msg.getTitle());
subView.setText(msg.getPUBDATE());
View.setText(_data.getTitle());
return v;
}
public class Font extends AsyncTask<TextView, Void, Boolean> {
@Override
protected Boolean doInBackground(TextView... params) {
// TODO Auto-generated method stub
String fontPath = "fonts/Qlassik_TB.ttf";
Typeface tf = Typeface.createFromAsset(_c.getAssets(), fontPath);
params[0].setTypeface(tf);
fontPath="fonts/damase.ttf";
tf = Typeface.createFromAsset(_c.getAssets(), fontPath);
params[1].setTypeface(tf);
tf = Typeface.createFromAsset(_c.getAssets(), fontPath);
params[3].setTypeface(tf);
return true;
}
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return _data.getMessages().size();
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return _data.getMessages().get(position);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
}
导入ru.ayratbadykov.feedhandler.FEED;
导入ru.ayratbadykov.feedhandler.RssMessage;
导入android.content.Context;
导入android.graphics.Typeface;
导入android.os.AsyncTask;
导入android.util.Log;
导入android.view.LayoutInflater;
导入android.view.view;
导入android.view.ViewGroup;
导入android.widget.BaseAdapter;
导入android.widget.TextView;
公共类CustomAdapter扩展了BaseAdapter{
私有FEED_数据;
语境;
CustomAdapter(提要数据,上下文c){
_数据=数据;
_c=c;
}
@凌驾
公共视图getView(int位置、视图转换视图、视图组父视图){
//TODO自动生成的方法存根
Log.w(“此处”、“此处”);
视图v=转换视图;
如果(v==null){
LayoutInflater vi=(LayoutInflater)\u c
.getSystemService(上下文布局\充气机\服务);
v=vi.充气(R.layout.customadapter,空);
}
TextView fromView=(TextView)v.findViewById(R.id.textView1);
TextView子视图=(TextView)v.findViewById(R.id.textView2);
TextView=(TextView)v.findViewById(R.id.textView3);
RssMessage msg=_data.getMessages().get(位置);
新建字体().execute(从视图、子视图、视图);
fromView.setText(msg.getTitle());
setText(msg.getPUBDATE());
View.setText(_data.getTitle());
返回v;
}
公共类字体扩展异步任务{
@凌驾
受保护的布尔doInBackground(TextView…参数){
//TODO自动生成的方法存根
字符串fontPath=“font/Qlassik_TB.ttf”;
Typeface tf=Typeface.createFromAsset(_c.getAssets(),fontPath);
参数[0]。设置字体(tf);
fontPath=“font/damase.ttf”;
tf=Typeface.createFromAsset(_c.getAssets(),fontPath);
参数[1]。设置字体(tf);
tf=Typeface.createFromAsset(_c.getAssets(),fontPath);
参数[3]。设置字体(tf);
返回true;
}
}
@凌驾
public int getCount(){
//TODO自动生成的方法存根
返回_data.getMessages().size();
}
@凌驾
公共对象getItem(int位置){
//TODO自动生成的方法存根
返回_data.getMessages().get(位置);
}
@凌驾
公共长getItemId(int位置){
//TODO自动生成的方法存根
返回位置;
}
}
日志
05-31 22:32:27.602:E/AndroidRuntime(2803):致命异常:AsyncTask#1
05-31 22:32:27.602:E/AndroidRuntime(2803):java.lang.RuntimeException:执行doInBackground()时出错
05-31 22:32:27.602:E/AndroidRuntime(2803):在android.os.AsyncTask$3.done(AsyncTask.java:200)
05-31 22:32:27.602:E/AndroidRuntime(2803):在java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274)
05-31 22:32:27.602:E/AndroidRuntime(2803):在java.util.concurrent.FutureTask.setException(FutureTask.java:125)
05-31 22:32:27.602:E/AndroidRuntime(2803):在java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308)
05-31 22:32:27.602:E/AndroidRuntime(2803):在java.util.concurrent.FutureTask.run(FutureTask.java:138)
05-31 22:32:27.602:E/AndroidRuntime(2803):位于java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
05-31 22:32:27.602:E/AndroidRuntime(2803):位于java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
05-31 22:32:27.602:E/AndroidRuntime(2803):在java.lang.Thread.run(Thread.java:1019)
05-31 22:32:27.602:E/AndroidRuntime(2803):原因:java.lang.RuntimeException:无法在未调用Looper.prepare()的线程内创建处理程序
05-31 22:32:27.602:E/AndroidRuntime(2803):位于android.os.Handler.(Handler.java:121)
05-31 22:32:27.602:E/AndroidRuntime(2803):在ru.ayratbadykov.rssunion.CustomAdapter$Font$1.(CustomAdapter.java:63)
05-31 22:32:27.602:E/AndroidRuntime(2803):在ru.ayratbadykov.rssunion.CustomAdapter$Font.doInBackground(CustomAdapter.java:63)
05-31 22:32:27.602:E/AndroidRuntime(2803):在ru.ayratbadykov.rssunion.CustomAdapter$Font.doInBackground(CustomAdapter.java:1)
05-31 22:32:27.602:E/AndroidRuntime(2803):在android.os.AsyncTask$2.call(AsyncTask.java:185)
05-31 22:32:27.602:E/AndroidRuntime(2803):在java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
05-31 22:32:27.602:E/AndroidRuntime(2803):。。。4更多
您可以在AsyncTask
中更新UI
,而不是从doInBackground()
进行更新。但任何其他方法都可以。由于它是适配器
类的一个内部类,包含对上下文
的引用,因此可以这样做。只需将使用Context
或需要更新UI
的代码移动到任何其他方法
例如,您可以将params
的ArrayList
返回到onPostExecute()
并在那里进行更新,也可以使用publishProgress()
在onProgressUpdate()中进行更新
因此也有很多很好的例子说明如何使用每种方法。AsyncTask允许您启动一个长流程,并通过UIThread方法访问UI:
- onPreExecute():在开始治疗前更新UI(doInBackground中的线程)
- onProgressUpdate():在治疗期间刷新UI
- onPostExecute():在进程结束时更新UI
你拥有一切
05-31 22:32:27.602: E/AndroidRuntime(2803): FATAL EXCEPTION: AsyncTask #1
05-31 22:32:27.602: E/AndroidRuntime(2803): java.lang.RuntimeException: An error occured while executing doInBackground()
05-31 22:32:27.602: E/AndroidRuntime(2803): at android.os.AsyncTask$3.done(AsyncTask.java:200)
05-31 22:32:27.602: E/AndroidRuntime(2803): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274)
05-31 22:32:27.602: E/AndroidRuntime(2803): at java.util.concurrent.FutureTask.setException(FutureTask.java:125)
05-31 22:32:27.602: E/AndroidRuntime(2803): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308)
05-31 22:32:27.602: E/AndroidRuntime(2803): at java.util.concurrent.FutureTask.run(FutureTask.java:138)
05-31 22:32:27.602: E/AndroidRuntime(2803): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
05-31 22:32:27.602: E/AndroidRuntime(2803): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
05-31 22:32:27.602: E/AndroidRuntime(2803): at java.lang.Thread.run(Thread.java:1019)
05-31 22:32:27.602: E/AndroidRuntime(2803): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
05-31 22:32:27.602: E/AndroidRuntime(2803): at android.os.Handler.<init>(Handler.java:121)
05-31 22:32:27.602: E/AndroidRuntime(2803): at ru.ayratbadykov.rssunion.CustomAdapter$Font$1.<init>(CustomAdapter.java:63)
05-31 22:32:27.602: E/AndroidRuntime(2803): at ru.ayratbadykov.rssunion.CustomAdapter$Font.doInBackground(CustomAdapter.java:63)
05-31 22:32:27.602: E/AndroidRuntime(2803): at ru.ayratbadykov.rssunion.CustomAdapter$Font.doInBackground(CustomAdapter.java:1)
05-31 22:32:27.602: E/AndroidRuntime(2803): at android.os.AsyncTask$2.call(AsyncTask.java:185)
05-31 22:32:27.602: E/AndroidRuntime(2803): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
05-31 22:32:27.602: E/AndroidRuntime(2803): ... 4 more
runOnUiThread(new Runnable(){
@Override
public void run(){
//update ui here
}
});
public class CustomAdapter extends BaseAdapter {
static Typeface mFont = YourClass.getDefaultTypeFace();
@Override
public View getView(int position, View convertView, ViewGroup parent) {
...
TextView tv;
...
tv.setTypeface(mFont);
...
}
}