Working with TextView,EditText

activity_main.xml:

<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"

    tools:context=".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="84dp"

        android:layout_marginTop="33dp"

        android:text="Large Text"

        android:textAppearance="?android:attr/textAppearanceLarge" />

    <Button

        android:id="@+id/button1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignLeft="@+id/textView1"

        android:layout_below="@+id/textView1"

        android:layout_marginLeft="16dp"

        android:layout_marginTop="96dp"

        android:text="ChangeText" />

</RelativeLayout>

public class MainActivity extends Activity {

TextView text;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        

        text = (TextView)findViewById(R.id.textView1);

        

        Button b = (Button)findViewById(R.id.button1);

        

        

        b.setOnClickListener(new OnClickListener() {

@Override

public void onClick(View arg0) {

// TODO Auto-generated method stub

text.setText("Hi ");

}

});

 }

Working with EditText:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/LinearLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Enter your name"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <EditText
        android:id="@+id/nameeditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="Enter name only"
        android:inputType="textPersonName" >
    </EditText>

    <Button
        android:id="@+id/showbutton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginTop="20dp"
        android:text="Show entered name" />

    <TextView
        android:id="@+id/nametextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge" />

</LinearLayout>

public class MainActivity extends Activity {

EditText editName;

TextView displayName;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        

        editName = (EditText)findViewById(R.id.nameeditText);

        displayName = (TextView)findViewById(R.id.nametextView);

        

        Button showNameBtn = (Button)findViewById(R.id.showbutton);

        

        

        showNameBtn.setOnClickListener(new OnClickListener() {

@Override

public void onClick(View arg0) {

// TODO Auto-generated method stub

String name = editName.getText().toString();

displayName.setText("entered name :"+name);

}

});

        

    }