Question

我是kotlin的新手，我想在kotlin中创建以下代码：

Fragment fragment = null;

switch(id) {
    case R.id.nav_new:
        fragment = new FragAllPosts();
        break;
    case R.id.nav_about:
        fragment = new FragAuthors();
        break;
    case R.id.nav_tags:
        fragment = new FragTags();
        break;
}

if (fragment != null) {
    FragmentTransaction ft = getFragmentManager().beginTransaction();
    ft.replace(R.id.content_frame, fragment);
    ft.commit();
}

这些片段非常基础，但还没有包含任何参数。如何在kotlin中实现上述目标？谢谢！

Answer 1

您可以将以下代码段作为示例：

var fragment: Fragment? = null
when(id) {
    R.id.nav_new -> fragment = FragAllPosts()
    R.id.nav_about -> fragment = FragAuthors()
    R.id.nav_tags -> fragment = FragTags()
}

if(null != fragment) {
    val ft = fragmentManager.beginTransaction();
    ft.replace(R.id.content_frame, fragment);
    ft.commit();
}

Answer 2

希望有帮助！

var fragment: Fragment? = null
when (id) {
    R.id.nav_new -> fragment = FragAllPosts.newInstance()
    R.id.nav_about -> fragment = FragAuthors.newInstance()
    R.id.nav_tags -> fragment = FragTags.newInstance()
}

// activity use supportFragmentManager
// fragment use childFragmentManager

fragment?.apply {
    supportFragmentManager?.beginTransaction()?.replace(R.id.content_frame, this)?.commit()
}

// Example class fragment create newInstance function

class FragAllPosts : Fragment() {
    companion object {
        fun newInstance(bundle: Bundle? = null): FragAllPosts = FragAllPosts().apply {
            arguments = bundle
        }
    }
}

kotlin中的片段实例化

2 个答案: