Android TableView - Fill from Hashtable


This tutorial explores how to fill an android tableview from a Hashtable data structure.

TableView allows us display tabular data in android.

TableView has the following features:

  • Rows.
  • Headers.
  • TableAdapter.

1. Create Basic Activity Project

  1. First create an empty project in android studio. Go to File --> New Project.

  2. Type the application name and choose the company name. New Project Dialog

  3. Choose minimum SDK. Choose minimum SDK

  4. Choose Basic activity. Choose Empty Activity

  5. Click Finish. Finish

Basic activity will have a toolbar and floating action button already added in the layout

Normally two layouts get generated with this option:

No. Name Type Description
1. activity_main.xml XML Layout Will get inflated into MainActivity Layout.Typically contains appbarlayout with toolbar.Also has a floatingactionbutton.
2. content_main.xml XML Layout Will be included into activity_main.xml.You add your views and widgets here.
3. MainActivity.java Class Main Activity.

In this example I used a basic activity.

The activity will automatically be registered in the android_manifest.xml. Android Activities are components and normally need to be registered as an application component.

If you've created yours manually then register it inside the <application>...<application> as following, replacing the MainActivity with your activity name:


        <activity android:name=".MainActivity">

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

You can see that one action and category are specified as intent filters. The category makes our MainActivity as launcher activity. Launcher activities get executed first when th android app is run.

Advantage of Creating Basic Activity project

You can optionally choose empty activity over basic activity for this project.

However basic activity has the following advantages:

No. Advantage
1. Provides us a readymade toolbar which gives us actionbar features yet easily customizable
2. Provides us with appbar layout which implements material design appbar concepts.
3. Provides a FloatinActionButton which we can readily use to initiate quick actions especially in examples like these.
4. Decouples our custom content views and widgets from the templating features like toolbar.

Generated Project Structure

AndroidStudio will generate for you a project with default configurations via a set of files and directories.

Here are the most important of them:

No. File Major Responsibility
1. build/ A directory containing resources that have been compiled from the building of application and the classes generated by android tools. Such a tool is the R.java file. R.java file normally holds the references to application resources.
2. libs/ To hold libraries we use in our project.
3. src/main/ To hold the source code of our application.This is the main folder you work with.
4. src/main/java/ Contains our java classes organized as packages.
5. src/main/res/ Contains our project resources folders as follows.
6. src/main/res/drawable/ Contains our drawable resources.
7. src/main/res/layout/ Contains our layout resources.
8. src/main/res/menu/ Contains our menu resources XML code.
9. src/main/res/values/ Contains our values resources XML code.These define sets of name-value pairs and can be strings, styles and colors.
10. AndroidManifest.xml This file gets autogenerated when we create an android project.It will define basic information needed by the android system like application name,package name,permissions,activities,intents etc.
11. build.gradle Gradle Script used to build the android app.

2. Add Dependencies

Add tableview dependencies in the app level build.gradle:

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:24.2.0'
    compile 'com.android.support:design:24.2.0'
    compile 'de.codecrafters.tableview:tableview:2.2.0'
}

3. Create User Interface

User interfaces are typically created in android using XML layouts as opposed by direct java coding.

This is an example fo declarative programming.

Advantages of Using XML over Java
No. Advantage
1. Declarative creation of widgets and views allows us to use a declarative language XML which makes is easier.
2. It's easily maintanable as the user interface is decoupled from your Java logic.
3. It's easier to share or download code and safely test them before runtime.
4. You can use XML generated tools to generate XML

Here are our layouts for this project:

activity_main.xml

  • This layout gets inflated to MainActivity user interface.
  • It includes the content_main.xml.

Here are some of the widgets, views and viewgroups that get employed"

No. View/ViewGroup Package Role
1. CordinatorLayout android.support.design.widget Super-powered framelayout that provides our application's top level decoration and is also specifies interactions and behavioros of all it's children.
2. AppBarLayout android.support.design.widget A LinearLayout child that arranges its children vertically and provides material design app bar concepts like scrolling gestures.
3. ToolBar <android.support.v7.widget A ViewGroup that can provide actionbar features yet still be used within application layouts.
4. FloatingActionButton android.support.design.widget An circular imageview floating above the UI that we can use as buttons.
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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:fitsSystemWindows="true"
    tools:context="com.tutorials.hp.tableviewhashtable.MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay" />

    </android.support.design.widget.AppBarLayout>

    <include layout="@layout/content_main" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        android:src="@android:drawable/ic_dialog_email" />

</android.support.design.widget.CoordinatorLayout>

content_main.xml

This layout gets included in your activity_main.xml. You define TableView here.

<?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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.tutorials.hp.tableviewhashtable.MainActivity"
    tools:showIn="@layout/activity_main">

    <de.codecrafters.tableview.TableView
        android:id="@+id/tableView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />

</RelativeLayout>

4. Java Classes

(a). Spaceprobe.java

This is our data object class. It represents a single spaceprobe.

package com.tutorials.hp.tableviewhashtable;

/**
 */
public class Spaceprobe {

    String id,name,propellant,destination;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPropellant() {
        return propellant;
    }

    public void setPropellant(String propellant) {
        this.propellant = propellant;
    }

    public String getDestination() {
        return destination;
    }

    public void setDestination(String destination) {
        this.destination = destination;
    }
}

(b). MainActivity.java

This is our MainActivity. We render our TableView here.

package com.tutorials.hp.tableviewhashtable;

import android.graphics.Color;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;

import java.util.Hashtable;
import java.util.Iterator;

import de.codecrafters.tableview.TableView;
import de.codecrafters.tableview.listeners.TableDataClickListener;
import de.codecrafters.tableview.toolkit.SimpleTableDataAdapter;
import de.codecrafters.tableview.toolkit.SimpleTableHeaderAdapter;

public class MainActivity extends AppCompatActivity {

    String[] spaceProbeHeaders={"ID","Name","Propellant","Destination"};
    String[][] spaceProbes;

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

        final TableView<String[]> tb = (TableView<String[]>) findViewById(R.id.tableView);
        tb.setColumnCount(4);
        tb.setHeaderBackgroundColor(Color.parseColor("#2ecc71"));

        //POPULATE
        populateData();

        //ADAPTERS
        tb.setHeaderAdapter(new SimpleTableHeaderAdapter(this,spaceProbeHeaders));
        tb.setDataAdapter(new SimpleTableDataAdapter(this, spaceProbes));

        tb.addDataClickListener(new TableDataClickListener() {
            @Override
            public void onDataClicked(int rowIndex, Object clickedData) {
                Toast.makeText(MainActivity.this, ((String[])clickedData)[1], Toast.LENGTH_SHORT).show();
            }
        });

    }
    private void populateData()
    {
        Spaceprobe spaceprobe=new Spaceprobe();
        Hashtable<Integer,Spaceprobe> spaceprobeTable=new Hashtable<>();

        spaceprobe.setId("1");
        spaceprobe.setName("Pioneer");
        spaceprobe.setPropellant("Solar");
        spaceprobe.setDestination("Venus");
        spaceprobeTable.put(0,spaceprobe);

        spaceprobe=new Spaceprobe();
        spaceprobe.setId("2");
        spaceprobe.setName("Casini");
        spaceprobe.setPropellant("Nuclear");
        spaceprobe.setDestination("Jupiter");
        spaceprobeTable.put(1,spaceprobe);

        spaceprobe=new Spaceprobe();
        spaceprobe.setId("3");
        spaceprobe.setName("Apollo");
        spaceprobe.setPropellant("Chemical");
        spaceprobe.setDestination("Moon");
        spaceprobeTable.put(2,spaceprobe);

        spaceprobe=new Spaceprobe();
        spaceprobe.setId("4");
        spaceprobe.setName("Enterpise");
        spaceprobe.setPropellant("Anti-Matter");
        spaceprobe.setDestination("Andromeda");
        spaceprobeTable.put(3,spaceprobe);

        spaceProbes= new String[spaceprobeTable.values().size()][4];

        Iterator it=spaceprobeTable.values().iterator();

        Spaceprobe s;
        int i=0;

        while (it.hasNext())
        {
            s= (Spaceprobe) it.next();
            spaceProbes[i][0]=s.getId();
            spaceProbes[i][1]=s.getName();
            spaceProbes[i][2]=s.getPropellant();
            spaceProbes[i][3]=s.getDestination();
            i++;
        }

    }
}

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