I have this main activity in android studio with error: adapter requires resource id textview

Question

I'm working on an android project which involves an array adapter and listview. However, when initizializing the arrayadpater I'm encountering some errors during runtime. error: java.lang.IllegalStateException: ArrayAdapter requires the resource ID to be a TextView I'm suspecting error on line 32 when initializing arrayadpater. Or maybe packagename and / or activity declaration in manifest file.... Any help appreciated

package org.pctechtips.menulistview;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
    ArrayList hosts;

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

        hosts = = new ArrayList<String>();
        hosts.add("192.168.10.100 | 33:00:11:aa:cc:bb");
        hosts.add("192.168.10.101 | 33:00:11:aa:cc:bb");
        hosts.add("192.168.10.102 | 33:00:11:aa:cc:bb");
        hosts.add("192.168.10.103 | 33:00:11:aa:cc:bb");
        hosts.add("192.168.10.104 | 33:00:11:aa:cc:bb");
        hosts.add("192.168.10.105 | 33:00:11:aa:cc:bb");
        hosts.add("192.168.10.106 | 33:00:11:aa:cc:bb");

        ListView list = (ListView) findViewById(R.id.list);
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.list_item, hosts);
        list.setAdapter(adapter);

    }

    /*
    * Infating the menu for toolbar
    */
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu, menu);
        return true;
    }

    /*
    * actions for menu options in toolbar
    */
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.change_icon) {
            Toast.makeText(getApplicationContext(), "Change Icon", Toast.LENGTH_SHORT).show();
            return true;
        }

        if (id == R.id.set_hostname) {
            Toast.makeText(getApplicationContext(), "Set Hostname", Toast.LENGTH_SHORT).show();
            return true;
        }

        if (id == R.id.notifications) {
            Toast.makeText(getApplicationContext(), "Notifications", Toast.LENGTH_SHORT).show();
        }

       return super.onOptionsItemSelected(item);
    }
}

list_menu.xml file

<?xml version="1.0" encoding="utf-8"?>
<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="wrap_content"
    android:orientation="horizontal">

    <LinearLayout
        android:id="@+id/text_container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <ImageView
            android:id="@+id/host_icon"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="0.20"
            android:padding="7dp"
            android:src="@drawable/computer_48_dp"/>

        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="0.60"
            android:orientation="vertical"
            android:paddingLeft="0dp"
            >

            <TextView
                android:id="@+id/ip_address"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:textSize="18dp"
                tools:text="192.168.10.100"
                />

            <TextView
                android:id="@+id/mac_address"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:textSize="16dp"
                tools:text="aa:bb:cc:00:11:22"
                />
        </LinearLayout>

    </LinearLayout>
</RelativeLayout>

main_activity.xml file

<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"
    tools:context=".MainActivity" >

    <LinearLayout android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="right"
        android:orientation="vertical">

        <ListView
            android:id="@+id/list"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>


    </LinearLayout>

</RelativeLayout>

Answer 1

You can use customize R.layout.list_item without mentioning the textview id as next parameter because without this the adapter internal code won't able to find the textview to bind data

 // another overloaded constructor 
 ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, 
                                    R.layout.list_item,R.id.YourTextViewID hosts);
 //                                                    ^^^^^^^^^^^^^^^^^

or

you make sure that your TextView has id as android:id="@android:id/text1"

Answer 2

You haven't posted your layout file for me to know if you're using a custom TextView or if you want to use the default Android provided TextView. You should have a TextView in the list_item_layout and reference it's ID in the ArrayAdapter adapter.

This Constructor takes the ID of the custom textview which you have defined

ArrayAdapter<String>(Context context, int resource, int textViewResourceId, T[] objects)

This constructor is for the ListView to use a default TextView with white background

ArrayAdapter<String>(this, int resource, T[] values)

The int resource value is given by android.R.layout.list_view and int textViewResourceID is given by android.R.id.list_item for a custom TextView