Ytukyg

I want to know why it tells me: "custom listview has stopped"? How can I solve it out?

This is my code in the Main Activity

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout 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"

    android:layoutDirection="rtl"

    android:padding="16dp"

    android:orientation="vertical"

    tools:context="customlistviews.oxbir.com.customlistview.ActivityMain">

    <EditText

        android:id="@+id/editTitle"

        android:layout_width="match_parent"

        android:layout_height="wrap_content" />

    <Button

        android:id="@+id/btnAdd"

        android:text="Add Row"

        android:layout_width="match_parent"

        android:layout_height="wrap_content" />

    <ListView

        android:id="@+id/listView"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_gravity="center_horizontal" />

</LinearLayout>

ActivityMain.java

package customlistviews.oxbir.com.customlistview;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.ListView;

import java.util.ArrayList;



public class ActivityMain extends AppCompatActivity {

    Button btnAdd;

    EditText editTitle;

    ArrayList<News> newsArrayList;

    ListView listView = (ListView)findViewById(R.id.listView);

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        editTitle = (EditText)findViewById(R.id.editTitle);

        btnAdd = (Button)findViewById(R.id.btnAdd);

        newsArrayList = new ArrayList<>();

        final NewsAdapter newsAdapter = new NewsAdapter(ActivityMain.this, R.layout.activity_customnews, newsArrayList);

        listView.setAdapter(newsAdapter);

        btnAdd.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                newsArrayList.add(new News(R.drawable.newsletter, editTitle.getText().toString()));

                newsAdapter.notifyDataSetChanged();

            }

        });

    }

}

activity_customnews.xml

<?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"

    android:padding="16dp"

    android:layoutDirection="rtl">

    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content">

        <ImageView

            android:id="@+id/imageNews"

            android:layout_width="100dp"

            android:layout_height="100dp"

            android:src="@drawable/newsletter" />

        <TextView

            android:id="@+id/txtTitle"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:textAlignment="center"

            android:layout_gravity="center"

            android:textSize="20dp"

            android:text="Title" />

    </LinearLayout>

</LinearLayout>

News.java

package customlistviews.oxbir.com.customlistview;



public class News {

    public int imageNews;

    public String titleNews;



    public News (int imageNews, String titleNews) {

        this.imageNews = imageNews;

        this.titleNews = titleNews;

    }

}

NewsAdapter.java

package customlistviews.oxbir.com.customlistview;



import android.app.Activity;

import android.media.Image;

import android.support.annotation.NonNull;

import android.support.annotation.Nullable;

import android.view.View;

import android.view.ViewGroup;

import android.widget.ArrayAdapter;

import android.widget.ImageView;

import android.widget.TextView;

import java.util.ArrayList;



public class NewsAdapter extends ArrayAdapter {

    public int resourceID;

    public Activity activity;

    public ArrayList<News> data;



    public NewsAdapter(Activity activity, int resourceID, ArrayList<News> object) {

        super(activity, resourceID, object);



        this.resourceID = resourceID;

        this.activity = activity;

        this.data = object;

    }



    @Override

    public View getView(int position, View convertView, ViewGroup parent) {

        View view = convertView;

        view = this.activity.getLayoutInflater().inflate(this.resourceID, null);

        ImageView imageView = (ImageView) view.findViewById(R.id.imageNews);

        TextView txtTitle = (TextView) view.findViewById(R.id.txtTitle);

        News news = data.get(position);

        imageView.setImageResource(R.drawable.newsletter);

        txtTitle.setText(news.titleNews);

        return view;

    }

}

Right now, I'm just trying to write something in a text field, and after every time I click on the button, I will display a photo and text that appears in my listview.

Your first error is in the line

ListView listView = (ListView)findViewById(R.id.listView);

in your main activity class.
You can not call findViewById before calling setContentView.

Member initialization happens when an object (of your activity class) is instantiated (the system calls new ActivityMain()) which is before onCreate is called.

So, findViewById will return null.

Then, when you try this:

listView.setAdapter(newsAdapter);

You will get a NullPointerException because you are trying to call setAdapter on a null reference.

There may be other errors, I did not read all your code, but this is the firs thing that will cause your app to crash.