Fragment的切换方法

Android开发中Fragment的切换有两方法

1、使用replace

public void replaceFragment(Fragment fragment) {
        FragmentManager fm = getSupportFragmentManager();
        FragmentTransaction transaction = fm.beginTransaction();
        transaction.replace(R.id.fragment_content, fragment);
        transaction.commit();
    }

使用该方法需要注意的是每一次切换Fragment的生命周期都会被调用一次
2、使用add-show-hide

    public void showFragment(int index) {
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        hideFragment(ft);
        switch (index) {
            case 0: {
                if(mHomeFragment == null) {
                    mHomeFragment = new HomeFragment();
                    ft.add(R.id.fragment_content,mHomeFragment);
                }else {
                    ft.show(mHomeFragment);
                }
                break;
            }
            case 1: {
                if(mTaskFragment == null) {
                    mTaskFragment = new TaskFragment();
                    ft.add(R.id.fragment_content,mTaskFragment);
                }else {
                    ft.show(mTaskFragment);
                }
                break;
            }
            default:
                break;
        }
        ft.commit();
    }


   public void hideFragment(FragmentTransaction ft){
        //如果不为空，就先隐藏起来
        if (mHomeFragment!=null){
            ft.hide(mHomeFragment);
        }
        if(mTaskFragment!=null) {
            ft.hide(mTaskFragment);
        }
    }

常用的方法
fragment.isAdded 判断是否被添加过