Android : Button, TextView and EditText

In this post we will discuss about 3 majorly used components in android.

1. TextView

Displays text to the user. You can take is as a label.

Important properties of TextView : 

android:id :- To define unique identity to your textview.

android:layout_width :- To define width of textview.

android:layout_height :- To define height of textview.

android:text :- To define text of textview.

Sample code :

<TextView
        android:id="@+id/tvName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Welcome to android" />

2. EditText 

EditText is a predefined subclass of TextView that includes rich editing capabilities.

Important properties of EditText : 

android:id :- To define unique identity to your EditText.

android:textColor :- To define text color of EditText contents.

android:editable : - If set, specifies that this EditText has an input method.

Sample Code :

<EditText android:id="@+id/edtName"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:hint="Enter UserName"

        android:textColor="#000000"/>

3. Button

A push-button that can be pressed, or clicked, by the user to perform an action.

Important properties of Button :

android:id :- To define unique identity to your Button.
android:background :- This is a drawable to use as the background.
android:onClick :- To define the method name which will be invoke when button is clicked.

Sample Code :

<Button android:id="@+id/btnSave"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Save"
        android:background="#FF0000"/>



Now we will develop one application with use of these controls.

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.textviewdemo"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="14" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.textviewdemo.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>

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"
    android:gravity="center_horizontal">

    <EditText android:id="@+id/edtName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:hint="Enter UserName"
        android:layout_alignParentTop="true"
        android:layout_marginTop="10dp"
        android:textColor="#000000"/>
 
    <Button android:id="@+id/btnSave"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:text="Save"
        android:layout_marginTop="10dp"
        android:layout_below="@+id/edtName"/>
 
    <TextView
        android:id="@+id/tvName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/btnSave"
        android:layout_marginTop="10dp"/>
 
</LinearLayout>

MainActivity,java

package com.ravi.textviewdemo;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {

    Button btnSave;
    EditText edtName;
    TextView tvName;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        btnSave=(Button)findViewById(R.id.btnSave);
        edtName=(EditText)findViewById(R.id.edtName);
        tvName=(TextView)findViewById(R.id.tvName);
        
        btnSave.setOnClickListener(this);
    }
 @Override
 public void onClick(View v) {
  // TODO Auto-generated method stub
  if(v.getId()==R.id.btnSave)
  {
   String name=edtName.getText().toString();
   tvName.setText("Welcome " + name);
  }
 }    
}

Output :