AndroidSpinner.doc

Spinner
It is used to create the drop down list of options from which we can select the option.
1.	Layout

<LinearLayout
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true">

    <Spinner
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/spinner" />

    <Button
        android:text="Button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/button" />

    <TextView
        android:text="TextView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/textView"
        android:textAppearance="@style/TextAppearance.AppCompat.Large" />
</LinearLayout>


2.	Java Code

public class MainActivity extends AppCompatActivity {

    TextView tv;
    Spinner sp;
    Button b1;
    String selected_item="";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        tv= (TextView) findViewById(R.id.textView);
        sp=(Spinner) findViewById(R.id.spinner);
        b1=(Button) findViewById(R.id.button);

        // Spinner Drop down elements
        List<String> op = new ArrayList<String>();
        op.add("CS");
        op.add("IT");
        op.add("EC");
        op.add("ME");
        op.add("CE");
        op.add("EE");

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, op);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        sp.setAdapter(adapter);

        sp.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int position, long l) {
                selected_item=sp.getItemAtPosition(position).toString();
            }

            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {

            }
        });


        b1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                tv.setText(selected_item);
            }
        });
    }
}