使用导航抽屉时可以加载fragment.java文件

Question

I am just wondering if it is possible to load a fragment.java file into the MainActivity that holds all the navigation drawer code. I will include code snippets to better explain myself.

MainActivity.java

@Override
public void onNavigationDrawerItemSelected(int position) {
    // update the main content by replacing fragments
    FragmentManager fragmentManager = getSupportFragmentManager();
    switch(position){
    case 0:
     fragmentManager.beginTransaction()
            .replace(R.id.container, SuikodenFragment.newInstance(position + 1)).commit();
     break;
    case 1:
        fragmentManager.beginTransaction()
            .replace(R.id.container, SuikodenIIFragment.newInstance(position + 1)).commit();
        break;
    case 2:
        fragmentManager.beginTransaction()
            .replace(R.id.container, SuikodenIIIFragment.newInstance(position + 1)).commit();
        break;
    case 3:
        fragmentManager.beginTransaction()
            .replace(R.id.container, SuikodenIVFragment.newInstance(position + 1)).commit();
        break;
    case 4:
        fragmentManager.beginTransaction()
            .replace(R.id.container, SuikodenVFragment.newInstance(position + 1)).commit();
        break;
    //similar for others
    }
}

The fragments in this code are also in MainActivity.java and they work. However, what I want to do is link a fragment.java file for each of these cases instead of the inline fragments listed here. The reason for this is that the fragment.java file will contain an Expandable ListView with Checkbox. Therefore, what is the best way to achieve this? Is there a line of code that will allow me load a fragment.java file?

Answer 1

Yes, it is possible.

You use the exact same code you are already using, but you replace SuikodenVFragment with the name of the Fragment class you want to use instead.

Say your project structure looks like this:

/com/example/myapp
  MainActivity.java
  SecondFragment.java

Then you can swap in an instance of SecondFragment by calling:

fragmentManager.beginTransaction().replace(R.id.container,
    SecondFragment.newInstance() // or new SecondFragment(), as appropriate
).commit();

The only "catch" is that you need to make sure that you import SecondFragment at the top of MainActivity.java with the rest of your imports. However, most IDEs will take care of this for you.

If you are new to Java and haven't used an import statement or packages before, I recommend starting with the Using Package Members guide from Oracle's Java tutorials.