How to make a horizontal line in Android application example code

public class MainComboBox extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Spinner spinner = (Spinner) findViewById(R.id.spinner);
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
                this, R.array.countries_array, android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(new MyOnItemSelectedListener());

        Button myButton =(Button)findViewById(R.id.button1);
        myButton.setOnClickListener(new Button.OnClickListener() {
            public void onClick(View v) {
            	
            Spinner sp =	(Spinner)findViewById(R.id.spinner);
            String spinnerString = null;
            spinnerString = sp.getSelectedItem().toString();
            int nPos = sp.getSelectedItemPosition();
            
             
                Toast.makeText(getApplicationContext(), "getSelectedItem=" + spinnerString,
                    Toast.LENGTH_LONG).show();
                Toast.makeText(getApplicationContext(), "getSelectedItemPosition=" + nPos,
                		Toast.LENGTH_LONG).show();
            }
        });
    }
}

public  class MyOnItemSelectedListener implements OnItemSelectedListener {

    public void onItemSelected(AdapterView<?> parent,
        View view, int pos, long id) {
      Toast.makeText(parent.getContext(), "Item is " +
          parent.getItemAtPosition(pos).toString(), Toast.LENGTH_LONG).show();
    }

    public void onNothingSelected(AdapterView parent) {
      // Do nothing.
    }
}

<resources>
    <string name="hello">Hello World, MainComboBox!</string>
    <string name="app_name">ComboBox</string>
    <string name="prompt">Choose a country</string>
    <string-array name="countries_array">
        <item>China</item>
        <item>India</item>
        <item>USA</item>
        <item>Indonesia</item>
        <item>Brazil</item>
        <item>Pakistan</item>
        <item>Nigeria</item>
        <item>Bangladesh</item>
        <item>Russia</item>
    </string-array>    
</resources>

<LinearLayout xmlns:android="//schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:padding="10dip"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content">
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dip"
        android:text="@string/prompt"
    />
    <Spinner 
        android:id="@+id/spinner"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:prompt="@string/prompt"
    />
    <Button android:text="Button" android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>

</LinearLayout>

       <cz.okhelp.wiktionary.CustomEditText
            android:id="@+id/editTextZadejSlovo"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="2"
            android:ems="10"
            android:hint="TypeAndPressGreen"
            android:singleLine="true"
            android:lines="1"
            android:maxLines="1" 
            android:drawableLeft="@drawable/cross"
            android:drawableRight="@drawable/ok" />
<!--button is invisible 0 height 0 width for performance click on button in EditText-->
        <Button
            android:id="@+id/btnGO"
            android:layout_width="0sp"
            android:layout_height="0sp"
            android:layout_weight="0"
            android:text="GO" />

package cz.okhelp.wiktionary; // your package name

import android.content.Context;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.widget.Button;
import android.widget.EditText;

public class CustomEditText extends EditText
{
  private Drawable dLeft,dRight;
  private Rect lBounds,rBounds;
  private static Button btnOk;

  public CustomEditText(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
  }
  public CustomEditText(Context context, AttributeSet attrs) {
    super(context, attrs);
  }
  public CustomEditText(Context context) {
    super(context);
  }

  @Override
  public void setCompoundDrawables(Drawable left, Drawable top,
      Drawable right, Drawable bottom)
  {
   if(left !=null) {
    	dLeft = left;
    }
   if(right !=null){
      dRight = right;
    } 
    
    super.setCompoundDrawables(left, top, right, bottom);
  }

	@Override
	public boolean onKeyUp(int keyCode, KeyEvent event) {
		if (keyCode == KeyEvent.KEYCODE_ENTER) {
    	btnOk.requestFocus();
    	btnOk.performClick();

		}
		return super.onKeyUp(keyCode, event);
	}
  
  @Override
  public boolean onTouchEvent(MotionEvent event)
  {
  	final int x = (int)event.getX();
  	final int y = (int)event.getY();

  	if(event.getAction() == MotionEvent.ACTION_UP && dLeft!=null) {
  		lBounds = dLeft.getBounds();
  		
  		int n1 = this.getLeft();
  		int n2 = this.getLeft()+lBounds.width();
  		int n3 = this.getPaddingTop();
  		int n4 = this.getHeight()-this.getPaddingBottom();
  		// leva strana
  		if(    x>=(this.getLeft()) 
  				&& x<=(this.getLeft()+lBounds.width())
  				&& y>=this.getPaddingTop() 
  				&& y<=(this.getHeight()-this.getPaddingBottom()))
  		{
  			this.setText("");
  			event.setAction(MotionEvent.ACTION_CANCEL);//use this to prevent the keyboard from coming up
  		}
  	}
  	if(event.getAction() == MotionEvent.ACTION_UP && dRight!=null)
    {
      rBounds = dRight.getBounds();
      int n1 = this.getRight()-rBounds.width();
      int n2 = this.getRight()-this.getPaddingRight();
      int n3 = this.getPaddingTop();
      int n4 = this.getHeight()-this.getPaddingBottom();
      // prava strana
      if(x>=(this.getRight()-rBounds.width()) && x<=(this.getRight()-this.getPaddingRight())
      		&& y>=this.getPaddingTop() && y<=(this.getHeight()-this.getPaddingBottom()))
      {
      	btnOk.requestFocus();
      	btnOk.performClick();
      	event.setAction(MotionEvent.ACTION_CANCEL);//use this to prevent the keyboard from coming up
      }
    }
    
    return super.onTouchEvent(event);
  }

  @Override
  protected void finalize() throws Throwable
  {
    dRight = null;
    rBounds = null;
    super.finalize();
  }
	public void setBtnOk(Button btnOk) {
		this.btnOk = btnOk;
	}
	public Button getBtnOk() {
		return btnOk;
	}
}  

//onCreate
        Button  mBtnGO = (Button)findViewById(R.id.btnGO);
        CustomEditText mEditZadani = (CustomEditText)this.findViewById(R.id.editTextZadejSlovo);
        mEditZadani.setBtnOk(mBtnGO);
        mBtnGO.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
             // do stuff for signInButtonClick
          }
        });

// file name MyFirstClass.java

import java.util.*;
import java.lang.Math;
import java.io.*;
import javax.swing.*;

public class MyFirstClass{ // start of program
  public static void main(String[] args) { // basic  function main

// variables and calculation
int a=2;
int b=3;
int c=Integer.parseInt(JOptionPane.showInputDialog(" Put number: ", "1"));
System.out.println("Number is: "+c);
System.out.println(a+" * "+b+" = "+(a*b));
System.out.println("a^3 "+Math.pow(a,b));

//array
int[] array_my=new int[10];
array_my[0]=3;
array_my[1]=5;
System.out.println("Number of elements "+array_my.length+" 1 + 2 element of array "+(array_my[0]+array_my[1]));

//strings
String txt="Quick red fox";
String txt2=JOptionPane.showInputDialog("Write text: ", "word");
System.out.println("Text is: "+txt2);
String[] count_of_word=txt.split(" ");
System.out.println("Length: "+txt.length()+" Count of words "+count_of_word.length);
System.out.println(txt +" -> "+txt.replace("red","brown"));
System.out.println("First 5 chars of string is: "+ txt.substring(0,5));

//for a if
for(int i=0; i<10;i++){
	if(i==3)System.out.println("i equal "+i);
	}

// file
try {
  File soubor=new File("some_file.txt");
  if(!soubor.exists()){
	System.out.println("File dont exist");
  }
  else { // utf-8 encoding
    BufferedReader in1 = new BufferedReader(new InputStreamReader(new FileInputStream(soubor),"UTF-8"));
    BufferedWriter out1 = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("zapis.txt"),"UTF-8"));
    String str;
      while ((str = in1.readLine())!=null){
        System.out.println(str);
        out1.write(str+"

");
      }
    in1.close();
    out1.close();
   }
 } catch(IOException e){System.out.println("Error " + e);}

// dir
 File pathName = new File("some_dir");
 String[] fileNames = pathName.list();
 if(pathName.exists())
 System.out.println("Name of first file in  "some_dir": "+fileNames[0]);
 else System.out.println("dir not exist");

//function
int nResult = calculateMyFc(3,5);
System.out.println("Result of function: "+nResult);

} // end of function main

// new function , you can add to end MyFc = my function
public static int calculateMyFc(int a, int b){
return (a+b);
}

} // end of class of program

String s = "AbcČ";
String s2 = s.toLowerCase(new Locale("cs_CZ")); // Czech Republic
String s3 = s.toLowerCase(new Locale("de_DE")); // Germany

//
en_US
en_GB
ar_EG
be_BY
bg_BG
ca_ES
cs_CZ
da_DK
de_DE