Android判断APP是否第一次启动

SharedPreferences setting = getSharedPreferences(SHARE_APP_TAG, 0);
	      Boolean user_first = setting.getBoolean("FIRST",true);
	      if(user_first){//第一次
	        	setting.edit().putBoolean("FIRST", false).commit();
	        	Toast.makeText(MainActivity.this, "第一次", Toast.LENGTH_LONG).show();
	       }else{
	    	   Toast.makeText(MainActivity.this, "不是第一次", Toast.LENGTH_LONG).show();
	      }