prime number java code

package com.example.user.myapp;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class SecondActivity extends AppCompatActivity {

    Button bprime;
    EditText editText;

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

        bprime = (Button) findViewById(R.id.b2);
        editText = (EditText) findViewById(R.id.e1);

        bprime.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String temp = editText.getText().toString();
                int num = Integer.parseInt(temp);

                int flag = 0;
                for (int i = 2; i < num; i++) {
                    if (num % i == 0) flag = 1;
                }

                if (flag == 0)
                    Toast.makeText(getApplicationContext(), "PRIME NUMBER!!!", Toast.LENGTH_LONG).show();
                else
                    Toast.makeText(getApplicationContext(), "NOT A PRIME NUMBER!!!", Toast.LENGTH_LONG).show();
            }
        });
    }
}