将活动转换为片段

Question

我是Android的新手，我试图将这个Activity变成一个Fragment但我不知道如何解决错误。

当我将其更改为Fragment时，我得到很多红色代码setContentView，findViewById和getMenuInflater。我知道这些可能是红色的，因为它们是用来Activities但我不确定它们要改成什么。

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.Menu;
import android.view.MenuItem;
public class LocationsFragment extends Fragment {
RecyclerView recyclerView;
RecyclerView.LayoutManager layoutManager;
RecyclerView.Adapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_card_demo);
// Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
// setSupportActionBar(toolbar);
recyclerView =
(RecyclerView) findViewById(R.id.recycler_view);
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
adapter = new RecyclerAdapter();
recyclerView.setAdapter(adapter);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_card_demo, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}

Answer 1

setContentView((

在碎片中没有这样的方法。相反，您可以覆盖onCreateView()并从中返回一些视图。您可以使用传入的LayoutInflater来膨胀通常传递给setContentView()的布局 ID，然后返回该 ID 。

findViewById((

片段没有findViewById()方法。但是，在onCreateView()返回后的任何时间，您都可以改用getView().findViewById()。在onCreateView()内部，如果你命名你的膨胀视图root你可以调用root.findViewById()。在onCreateView()之前，没有办法查找任何视图(因为它们还没有膨胀(。

getMenuInflater((

片段对onCreateOptionsMenu()使用不同的签名。它看起来像这样：

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
// ...
}

您可以使用传入的MenuInflater而不是调用getMenuInflater()。

---

把这些放在一起，这就是你会得到的：

public class LocationsFragment extends Fragment {
RecyclerView recyclerView;
RecyclerView.LayoutManager layoutManager;
RecyclerView.Adapter adapter;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.activity_card_demo, container, false);
recyclerView = (RecyclerView) root.findViewById(R.id.recycler_view);
layoutManager = new LinearLayoutManager(getContext());
recyclerView.setLayoutManager(layoutManager);
adapter = new RecyclerAdapter();
recyclerView.setAdapter(adapter);
return root;
}
@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.menu_card_demo, menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}