调用引发异常的方法

Question

I am writing an app to pull and display content from an atom feed. The method for that works, but I get the error " Unhandled exception: java.lang.Exception " when I try to call the method " showFeed() " in onNavigationItemSelected .

package com.myapp;
import java.net.URL;
import java.util.Iterator;
import com.sun.syndication.feed.synd.SyndEntry;
import com.sun.syndication.feed.synd.SyndFeed;
import com.sun.syndication.io.SyndFeedInput;
import com.sun.syndication.io.XmlReader;

// ... 

public boolean onNavigationItemSelected(@NonNull MenuItem item) {
    switch (item.getItemId()) {
        case R.id.navigation_home:
            showFeed();
    }
}

// ...

public void showFeed() throws Exception {

    URL url = new URL("http://feeds.feedburner.com/javatipsfeed");
    XmlReader xmlReader = null;

    try {

        xmlReader = new XmlReader(url);
        SyndFeed feeder = new SyndFeedInput().build(xmlReader);
        System.out.println("Title Value " + feeder.getAuthor());

        for (Iterator iterator = feeder.getEntries().iterator(); iterator.hasNext();) {
            SyndEntry syndEntry = (SyndEntry) iterator.next();
            System.out.println(syndEntry.getTitle());
        }
    } finally {
        if (xmlReader != null)
            xmlReader.close();
    }

}

I want to call this method in onNavigationItemSelected .

Answer 1

Your showFeed method is throwing Exception,

public void showFeed() throws Exception

This has to be caught using try-catch block or thrown further from the caller method which is onNavigationItemSelected

So either catch it like this,

 case R.id.navigation_home:
try{
            showFeed();
} catch (Exception e) {
e.printStackTrace();
}

Or throw it again like below,

public boolean onNavigationItemSelected(@NonNull MenuItem item) throws Exception

Answer 2

You are running network related threads on UI Thread which may cause ANR (Activity not responding) Follow the following tutorial.

Android AsyncTask example and explanation