How to let a user add and remove items to a ListView?

Question

I am trying to make it so that when a user clicks a button, it pops up a dialog with an EditText and an OK Button. When the user completes, the dialog, it should add the item they just typed in to the ListView. How do I do this?

I will need a large code example; this is my first application.

Answer 1

Well here is a sample code. There is a button to add text in list and long press on list item will remove it.

activity_main.xml

<LinearLayout 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:orientation="vertical" >

<Button
    android:id="@+id/button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:text="Add Item" />

<ListView
    android:id="@+id/list_view"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" />

dialog_layout.xml

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

<EditText
    android:id="@+id/edit_box"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginLeft="10dp"
    android:layout_marginRight="10dp"
    android:inputType="text" />

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginLeft="10dp"
    android:layout_marginRight="10dp"
    android:orientation="horizontal"
    android:weightSum="2" >

    <Button
        android:id="@+id/button_ok"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="OK" />

    <Button
        android:id="@+id/button_cancel"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="CANCEL" />
</LinearLayout>

MainActivity.java

package com.example.listexample;

import java.util.ArrayList;

import android.app.Activity;
import android.app.Dialog;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.BaseAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends Activity implements OnClickListener,
        OnItemLongClickListener {

    private ArrayList<String> datasource;
    private MyAdapter adapter;
    private Dialog dialog;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        datasource = new ArrayList<String>();
        adapter = new MyAdapter();
        ListView listView = (ListView) findViewById(R.id.list_view);
        listView.setAdapter(adapter);
        listView.setOnItemLongClickListener(this);

        findViewById(R.id.button).setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                dialog = new Dialog(MainActivity.this);
                dialog.setContentView(R.layout.dialog_layout);
                dialog.findViewById(R.id.button_cancel).setOnClickListener(
                        MainActivity.this);
                dialog.findViewById(R.id.button_ok).setOnClickListener(
                        MainActivity.this);
                dialog.show();
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    private class MyAdapter extends BaseAdapter {

        @Override
        public int getCount() {
            // TODO Auto-generated method stub
            return datasource.size();
        }

        @Override
        public Object getItem(int position) {
            // TODO Auto-generated method stub
            return datasource.get(position);
        }

        @Override
        public long getItemId(int position) {
            // TODO Auto-generated method stub
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            TextView view = (TextView) convertView;
            if (null == view) {
                view = new TextView(MainActivity.this);
                view.setPadding(10, 10, 10, 10);
            }
            view.setText(datasource.get(position));
            return view;
        }
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
        case R.id.button_cancel:
            dialog.dismiss();
            break;

        case R.id.button_ok:
            String text = ((EditText) dialog.findViewById(R.id.edit_box))
                    .getText().toString();
            if (null != text && 0 != text.compareTo("")) {
                datasource.add(text);
                dialog.dismiss();
                adapter.notifyDataSetChanged();
            }

            break;
        }
    }

    @Override
    public boolean onItemLongClick(AdapterView<?> listView, View view,
            int position, long column) {
        datasource.remove(position);
        adapter.notifyDataSetChanged();
        return true;
    }
}

Answer 2

You'll want to follow the official notepad tutorial example. It's very comprehensive. It does 95% of what you want to do.

http://developer.android.com/resources/tutorials/notepad/index.html