// 初始化默认显示的界面		if (purchaserHomeFragment == null) {			purchaserHomeFragment = new PurchaserHomeFragment();			addFragment(purchaserHomeFragment);			showFragment(purchaserHomeFragment);		} else {			showFragment(purchaserHomeFragment);		}		// 购物车界面			if (purchaserCarFragment == null) {				purchaserCarFragment = new PurchaserCarFragment();				// 判断当前界面是否隐藏，如果隐藏就进行添加显示，false表示显示，true表示当前界面隐藏				if (!purchaserCarFragment.isHidden()) {					addFragment(purchaserCarFragment);					showFragment(purchaserCarFragment);				}			} else {				if (purchaserCarFragment.isHidden()) {					showFragment(purchaserCarFragment);				}			}				/** 添加fragment **/	public void addFragment(Fragment fragment) {		FragmentTransaction ft = this.getSupportFragmentManager().beginTransaction();		ft.add(R.id.fl_content, fragment);		ft.commit();	}	/** 显示fragment **/	public void showFragment(Fragment fragment) {		FragmentTransaction ft = this.getSupportFragmentManager().beginTransaction();		// 判断页面是否已经创建，如果已经创建，那么就隐藏掉		if (purchaserHomeFragment != null) {			ft.hide(purchaserHomeFragment);		}		if (purchaserTypeFragment != null) {			ft.hide(purchaserTypeFragment);		}		if (purchaserOrderFragment != null) {			ft.hide(purchaserOrderFragment);		}		if (purchaserCarFragment != null) {			ft.hide(purchaserCarFragment);		}		ft.show(fragment);		ft.commitAllowingStateLoss();	}