CODEWITHSUNDEEP
androidlistviewnullcrashlistadapter
Williams Diaz
Williams Diaz

Reputation: 23

List Crashes App when updated

I'm trying to get a ListView to show the contents of a simple array but my program crashes at the setAdapeter line. As I understand this is supposed to be because the final value comes out as null but I don't see why that would be the case or how to fix it. I have already tried using ArrayAdapeter instead as well as catching the null exception with a try block. The former changes nothing and the latter simply shows a blank activity with no list to speak of. Please help.

Here's Main Activity

package ballton.fowdeckbuilder;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ListAdapter;
import android.widget.ArrayAdapter;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

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

    Button btnDecks = (Button) (findViewById(R.id.btnDecks));
    Button btnCards = (Button) (findViewById(R.id.btnCards));

    btnDecks.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            startActivity(new Intent(MainActivity.this, DeckCatalogue.class));
        }
    });

    btnCards.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            startActivity(new Intent(MainActivity.this, CardCatalogue.class));
        }
    });
}
}

Here's the activity with the Problem

    package ballton.fowdeckbuilder;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;

public class DeckCatalogue extends AppCompatActivity {

ListView Ldecks;
String TAG = "TAG";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_deck_catalogue);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    Ldecks = (ListView) (findViewById(R.id.DeckList));

    String Decks[] = new String[] {"Faria","Melgis"};

    ListAdapter feed = (new ArrayAdapter<String>(this, R.layout.show_deck, Decks));

    Ldecks.setAdapter(feed);
}

}

Here's the Layout for that activity

 <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="ballton.fowdeckbuilder.DeckCatalogue"
tools:showIn="@layout/activity_deck_catalogue">

<ListView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/DeckList"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />
</RelativeLayout>

And Here's the layout XML I use for the list times

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceSmall"
    android:text="Small Text"
    android:id="@+id/Deck" />
</LinearLayout>

Upvotes: 2

Views: 70

Answers (1)

Rubel Hassan
Rubel Hassan

Reputation: 186

Use this code instead of yours:

ListAdapter feed = (new ArrayAdapter<String>(this, R.layout.show_deck, R.id.Deck, Decks));

This happened because you must supply the resource ID (as your xml: R.id.Deck) for the TextView you used for ListView.

Upvotes: 1

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