استاپ شدن برنامه

 package com.example.majid.devisions;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
  TextView txt_result;
  Button btn_compute;

  public void devisions(int num){
    int i;
    for(i=1; i<= num; i++){
      if(num %i==0){
        txt_result.setText(txt_result.getText().toString()+("A Devision Is = " + i) + "\n" );
      }
    }
  }

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    View.OnClickListener listener = new View.OnClickListener() {
      @Override
      public void onClick(View v) {

      }
    };

    btn_compute.setOnClickListener(listener);

      txt_result = (TextView) findViewById(R.id.txt_result);
      btn_compute = (Button) findViewById(R.id.btn_compute);

    devisions(8);

  }
}