When button clicked the app was Force Close

I had make every activity Random if a button clicked but it seemsly not working good, the game was force close.

this is the following code

public class menu extends Activity {


    int time = 5, one, two, three, four, five, number;
    RelativeLayout layout1, layout2;
    Button button1; 

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
        WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.menu);

        SharedPreferences pref = getSharedPreferences("SavedGame", MODE_PRIVATE); 
        SharedPreferences.Editor editor = pref.edit();      
        editor.putInt("Lifes", 6);
        editor.putInt("Level", 0);  
        editor.putInt("One", 1);  
        editor.putInt("Two", 1);  
        editor.putInt("Three", 1);  
        editor.putInt("Four", 1); 
        editor.putInt("Five", 1);  


        editor.commit();


        layout1 =(RelativeLayout)findViewById(R.id.layout1);
        layout2 =(RelativeLayout)findViewById(R.id.layout2);


          new CountDownTimer(5000, 1000) {

          @Override
          public void onFinish() {        
              layout1.setVisibility(View.GONE);
              layout2.setVisibility(View.VISIBLE);
          }

          @Override
          public void onTick(long millisUntilFinished) {
          }
         }.start();  


        button1 = (Button)findViewById(R.id.introbutton1);
        button1.setOnClickListener(new View.OnClickListener() {

            public void onClick(View v){            
            SharedPreferences pref = getSharedPreferences("SavedGame", MODE_PRIVATE); 
            SharedPreferences.Editor editor = pref.edit();      
            editor.putInt("Level", 1);  
            editor.commit();


         // Here, we are generating a random number
         Random generator = new Random();
         number = generator.nextInt(5) + 1; 
         // The '5' is the number of activities

         Class activity = null;

         // Here, we are checking to see what the output of the random was
         switch(number) { 
         // E.g., if the output is 1, the activity we will open is ActivityOne.class


             case 1: if(one == 1){
                 activity = activityone.class;
                 }

// if the activity was aready opened he will put value == 2, so the code will random again find activity with value == 1
                else if(one == 2){
                    Random generatorone = new Random();
                    number = generatorone.nextInt(5) + 1; 
                }

                 break;
             case 2: if(two== 1){
                 activity = activitytwo.class;
                 }
                else if(two== 2){
                    Random generatortwo = new Random();
                    number = generatortwo.nextInt(5) + 1; 
                }
                 break;
             case 3:if(three== 1){
                 activity = activitythree.class;
                 }
                else if(three== 2){
                    Random generatorthree = new Random();
                    number = generatorthree.nextInt(5) + 1; 
                }
                 break;
             case 4:if(four == 1){
                 activity = activityfour.class;
                 }
                else if(four == 2){
                    Random generatorFour = new Random();
                    number = generatorFour.nextInt(5) + 1; 
                }               

                 editor = pref.edit();
                 // Key,Value
                 editor.putInt("Activity", number);

                 editor.commit();      
                 }
         // We use intents to start activities
         Intent intent = new Intent(getBaseContext(), activity);
         startActivity(intent);
            }
         });
     }

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
  }

but when i click the button, the app was force close. Did i missing something? anyone can help?