package com.apress.gerber.file_demo1;

import android.app.Activity;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.Toast;

import java.io.File;
import java.io.IOException;

public class MainActivity extends Activity {

   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
      File file= new File(Environment.getExternalStorageDirectory(),"text.xml");
      if(!file.exists())
      {
          try {
              file.createNewFile();
          } catch (IOException e) {
              e.printStackTrace();
          }

      }else {
          Toast.makeText(MainActivity.this,"文件已经存在",1000);

      }

   }
}