CODEWITHSUNDEEP
javaandroid
codez
codez

Reputation: 1532

Android CustomListViewAdapter behaving weirdly when data is removed

Basically, this is the relevant chunk of code of the MainActivity class:

private ListView listView;
private ArrayList<String> tasks = new ArrayList<String>();

private CustomListViewAdapter customListViewAdapter;

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

    tasks.add("Hfrfello");
    tasks.add("Heefrefllo");
    tasks.add("Hellefrefo");
    tasks.add("Helggglo");
    tasks.add("Helggglo");
    tasks.add("aaHello");
    tasks.add("aaaaaaHelaaalo");
    tasks.add("Hfrfello");
    tasks.add("Heefrefllo");
    tasks.add("Hellefrefo");
    tasks.add("Helggglo");
    tasks.add("Helggglo");
    tasks.add("aaHello");
    tasks.add("aaaaaaHelaaalo");

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

    this.customListViewAdapter = new CustomListViewAdapter(getApplicationContext(), this.tasks);

    this.listView.setAdapter(this.customListViewAdapter);

    this.listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            //deleteTask(position);

            customListViewAdapter.remove(position);
            //tasks.remove(position);
            customListViewAdapter.notifyDataSetChanged();
        }
    });
}

And this is my CustomListViewAdapter class:

package com.hassanalthaf.dailytaskmanager;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;

public class CustomListViewAdapter extends BaseAdapter {
    private Context context;
    private ArrayList<String> tasks;
    private static LayoutInflater inflater = null;

    public CustomListViewAdapter(Context context, ArrayList<String> data) {
        this.context = context;
        this.tasks = data;
        this.inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        return this.tasks.size();
    }

    @Override
    public Object getItem(int position) {
        return position;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    public void remove(int position) {
        this.tasks.remove(position);
        System.out.println(this.tasks);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = convertView;

        if (convertView == null) {
            view = this.inflater.inflate(R.layout.list_row, null);

            TextView taskName = (TextView) view.findViewById(R.id.taskName);
            ImageView image = (ImageView) view.findViewById(R.id.deleteButton);

            String task = this.tasks.get(position);

            taskName.setText(task);
        }

        return view;
    }
}

My issue: When I click on my Graphical User Interface, it does delete and update the ListView, however, it updates it wrong. What it does is, when I click on the first 3 elements(which should delete them), it does delete them from the ArrayLists and I get the right output after getting rid of them. However, in the user interface, instead of deleting what I clicked, it just removes the bottom items, and doesn't touch the top ones. How would I solve this issue?

Upvotes: 0

Views: 54

Answers (2)

c__c
c__c

Reputation: 1612

I agreed with @cybersam. I think it would be optimized if you use the Holder pattern as:

@Override 
public View getView(int position, View convertView, ViewGroup parent) {        
    MyHolder holder;
    View view = convertView;

    if (view == null) {
        view = this.inflater.inflate(R.layout.list_row, null);
        holder = new MyHolder(view);
        view.setTag(holder);
    }
    else
    {
       holder = (MyHolder) view.getTag();
    }


    String task = this.tasks.get(position);
    holder.taskName.setText(task);

    return view;
} 



 class MyHolder {
        TextView taskName;

        public MyHolder(View view) {
            taskName = (TextView) view.findViewById(R.id.taskName);
        }
    }

Upvotes: 1

cybersam
cybersam

Reputation: 67019

Your getView() is not setting the state of recycled convertView objects, so they continue to show the old state. Try this:

@Override 
public View getView(int position, View convertView, ViewGroup parent) {
    View view = convertView;

    if (convertView == null) {
        view = this.inflater.inflate(R.layout.list_row, null);
    }

    TextView taskName = (TextView) view.findViewById(R.id.taskName);
    String task = this.tasks.get(position);
    taskName.setText(task);

    return view;
}

Upvotes: 1

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