why my code (http connection android) doesn't work

Question

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hi Guys !
im trying to make simple app to connect internet. but it doesn't work !
& i dont know why ?! i also searched Google to find Simple exampels but i didnt find anything usefull .
please help me and fix my mistakes .
tnx

error:
java.lang.NullPointerException: println needs a message
W/IInputConnectionWrapper(2880): showStatusIcon on inactive InputConnection

Code :

Java

package net.learn2develop.http3;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import android.util.Log;
import android.widget.TextView;

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		
		
		
		
		Log.d("location", " 0 as start");
		
		InputStream in=null;
		int response=-1;
		String urlString="http://www.tabnak.ir";
		try
		{
		URL url=new URL(urlString);
		URLConnection conn=url.openConnection();
		if(!(conn instanceof  HttpURLConnection))
		throw new IOException("Not ann HTTP Connection");
		try
		{
			HttpURLConnection httpConn=(HttpURLConnection)conn;
			httpConn.setAllowUserInteraction(false);
			httpConn.setInstanceFollowRedirects(true);
			httpConn.setRequestMethod("GET");
			httpConn.connect();
			response=httpConn.getResponseCode();
			if(response==HttpURLConnection.HTTP_OK)
			{in=httpConn.getInputStream();}
			else{ 
				Log.d("location", " 1");
				}
			TextView intxt=(TextView)findViewById(R.id.mytxt); 
			intxt.setText(in.toString());
			
		}
		catch(Exception ex0)
		{
			Log.d("e:",ex0.getLocalizedMessage());
		}
		
		}
		catch(Exception ex)
		{
			Log.d("location 2 Exception : ", ex.toString());
		}
		
		
		

		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		
		
		
	}

AndroidManifest.xml :

XML

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="net.learn2develop.http3"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />
 <uses-permission android:name="android.permission.INTERNET"/>
 <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/> 
    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="net.learn2develop.http3.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

UI :

XML

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/mytxt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

</RelativeLayout>

Posted 30-Nov-14 4:54am

seyed mahmud shahrokni

Updated 30-Nov-14 4:58am

v3

Add a Solution

Comments

DamithSL 30-Nov-14 11:50am

try to dispose the stream

intxt.setText(in.toString());
in.close();;

seyed mahmud shahrokni 30-Nov-14 12:18pm

it doesnt work !

3 solutions

Solution 1

java.lang.NullPointerException

One of the basic errors that you need to understand. You have a reference object somewhere that has not been initialized to refer to anything. Use your debugger to find out where it is.

Also, your code would be much easier to read if you made better use of spaces and newlines.

Posted 30-Nov-14 5:12am

Richard MacCutchan

Comments

seyed mahmud shahrokni 30-Nov-14 12:26pm

have you ever read my Code ?!
do you know anything about Difference between suggestion and Solution !?
if you have a suggestion you can use Comments , right ?
sorry man but i want a solution ! a peace of code you know !
i know how can i use my debugger ! and i did that !
but i cant find problem !
its an easy question for someone like you , but im new in android ! ok ?
i know you can solve it in a minute ! but you dont want .

Richard MacCutchan 1-Dec-14 3:14am

Vitriolic attacks such as this will not endear you to this community.

Richard MacCutchan 1-Dec-14 3:18am

Yes I have read your code, and somewhere in there you have a NULL pointer, which is impossible to identify without using the debugger. But if you are too lazy to make the effort why do you think anyone else would?

Solution 3

I solved it mySelf !

Java

package com.example.html5;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import java.net.URL;
import java.net.URLConnection;
import java.net.HttpURLConnection;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import android.widget.TextView;
import android.util.Log;
import android.os.AsyncTask;

public class MainActivity extends Activity {
	
	
	
	
	
	protected String ShowHtml()
	{
		//TextView myTxt=(TextView)findViewById(R.id.txtReturn); 
		HttpURLConnection urlConnection = null;
		String line="Start:";
		try
		{
		URL myUrl=new URL("http://google.com");
		urlConnection = (HttpURLConnection)myUrl.openConnection();
		BufferedReader in = new BufferedReader (new InputStreamReader(urlConnection.getInputStream()));
		
		//int Counter=0;
		while(in.readLine()!=null)
		{
			line=line+in.readLine().toString();
			//Counter++;
		}
		
	//	myTxt.setText(line);
		}
		catch(Exception ex0)
		{
		Log.d("Error : ",ex0.toString());
	//	myTxt.setText(ex0.toString());
		}
		finally
		{
			if(urlConnection!=null){urlConnection.disconnect(); 	}
			
			
		}
		return line;
		
	}
	
	
	
	
	
	class RetrieveFeedTask extends AsyncTask<string,> {

	    

	    protected String doInBackground(String... urls) {
	    	try
	    	{
	        return ShowHtml();
	    	}
	    	catch(Exception e)
	    	{
	    	return e.toString();
	    	}
	    }

	    protected void onPostExecute(String Result) {
	    	TextView mytxt2=(TextView)findViewById(R.id.txtReturn);
	    	mytxt2.setText(Result);
	      
	    }
	}

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		new RetrieveFeedTask().execute();
	}

	

}

Posted 2-Dec-14 9:36am

seyed mahmud shahrokni

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Xiao Ling · Accepted Answer · 2014-11-30T19:03:00

Solution 2

Move your HTTP connection code to a worker thread. The network I/O will cause crash in UI thread (onCreate).

Posted 30-Nov-14 19:03pm

Xiao Ling