Hello World Example

Hello World Example:

1.Layout XML File:

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    tools:context=".HelloWorldExample_MainActivity" >

    <TextView

        android:id="@+id/textView1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignParentLeft="true"

        android:layout_alignParentTop="true"

        android:layout_marginLeft="34dp"

        android:layout_marginTop="26dp"

        android:text="Enter Name" />

    <EditText

        android:id="@+id/name_editText1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignLeft="@+id/textView1"

        android:layout_below="@+id/textView1"

        android:ems="10" >

        <requestFocus />

    </EditText>

    <Button

        android:id="@+id/button1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignLeft="@+id/name_editText1"

        android:layout_below="@+id/name_editText1"

        android:layout_marginLeft="48dp"

        android:layout_marginTop="30dp"

        android:onClick="welcome"

        android:text="Submit" />

    <TextView

        android:id="@+id/textView2"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignParentLeft="true"

        android:layout_centerVertical="true"

        android:layout_marginLeft="28dp"

        android:text="Welcome" />

</RelativeLayout>

  

   After writing this much code you will get Following UI screen:

   // We dont have to write everything by ourself ,we can do just drag and drop from Palette.

2. .JAVA file for our Activity :

package com.solomon.HelloWorldExample;

import android.os.Bundle;

import android.app.Activity;

import android.view.Menu;

import android.view.View;

import android.widget.EditText;

import android.widget.TextView;

public class HelloWorldExample_MainActivity extends Activity {

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.hello_world_example__main);

}

@Override

public boolean onCreateOptionsMenu(Menu menu) {

// Inflate the menu; this adds items to the action bar if it is present.

getMenuInflater().inflate(R.menu.hello_world_example__main, menu);

return true;

}

public void welcome(View view) {

//While clicking button1 this welcome method will call of onclick.

String name;

TextView welcomeTextView;

EditText nameEditText;

nameEditText=(EditText)findViewById(R.id.name_editText1);

//Using EditText we can get values from user

//Here,I am getting a name and storing in nameEditText

welcomeTextView=(TextView)findViewById(R.id.textView2);

//TextView is more like a Label.

name=nameEditText.getText().toString();

//Getting Text from EditText and storing it in name(local variable).

welcomeTextView.setText("Hello"+name+".Welcome to Android World");

//whatever value stored in name is added with 2 more string and stored in WelcomeTextView.

}

}

3.AndroidMainfest File:

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

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.solomon.HelloWorldExample"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk

        android:minSdkVersion="8"

        android:targetSdkVersion="18" />

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

        <activity

            android:name="com.solomon.HelloWorldExample.HelloWorldExample_MainActivity"

            android:label="@string/app_name" >

            <intent-filter>

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

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

            </intent-filter>

        </activity>

    </application>

</manifest>

4.Output: