Question

对于我的主要详细信息流应用，我试图在我的平板电脑上对我的大陆列表视图进行充气，但它不会这样做，我最终在我的日志猫中出现了这些错误。有谁知道我做错了什么？

大陆列表xml

menu = [
    # TODO: define your encrypt, decrypt and secure_encrypt functions
    ("Encrypt message", encrypt),
    ("Decrypt message", decrypt),
    ("Secure Encrypt Message", secure_encrypt),
    ("Exit", sys.exit),
    ]
for n, (label, _) in enumerate(menu, start=1):
    print("{}) {}".format(n, label))
selection = input("Please select: ")
assert 1 <= selection <= len(menu), "TODO: better error handling"
menu[selection - 1][1]()

ContinentsListActivity.java

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:layout_marginLeft="16dp"
    android:layout_marginRight="16dp" android:baselineAligned="false"
    android:divider="?android:attr/dividerHorizontal" android:orientation="horizontal"
    android:showDividers="middle" tools:context=".ItemListActivity">

    <fragment android:id="@+id/continents_list" android:name="com.apptacularapps.md.ContinentsListFragment"
        android:layout_width="0dp" android:layout_height="match_parent" android:layout_weight="1"
        tools:layout="@android:layout/list_content" />

    <FrameLayout android:id="@+id/item_detail_container" android:layout_width="0dp"
        android:layout_height="match_parent" android:layout_weight="3" />

</LinearLayout>

ContinentsListFragment.java

import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;

public class ContinentsListActivity extends ActionBarActivity
        implements ContinentsListFragment.Callbacks {

    private boolean mTwoPane;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_continents_list);

        FragmentManager fm = getFragmentManager();
        FragmentTransaction ft = fm.beginTransaction();
        ft.replace(R.id.continents_list_contaniner, new ContinentsListFragment());
        ft.commit();

        if (findViewById(R.id.item_detail_container) != null) {
            mTwoPane = true;

            ((ContinentsListFragment) getSupportFragmentManager()
                    .findFragmentById(R.id.continents_list))
                    .setActivateOnItemClick(true);
        }

    }

    @Override
    public void onItemSelected(String id) {
        if("1".equals(id)){
            if (mTwoPane) {

                Bundle arguments = new Bundle();
                arguments.putString(ItemDetailFragment.ARG_ITEM_ID, id);
                ItemDetailFragment fragment = new ItemDetailFragment();
                fragment.setArguments(arguments);
                getSupportFragmentManager().beginTransaction()
                        .replace(R.id.continents_list, fragment)
                        .commit();

            } else {
                Intent detailIntent = new Intent(this, ContinentsListActivity.class);
                startActivity(detailIntent);
            }
        }
    }
}

logcat的

    package com.apptacularapps.md;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class ContinentsListFragment extends ListFragment {

    private static final String STATE_ACTIVATED_POSITION = "activated_position";

    private Callbacks mCallbacks = sContinentsCallbacks;

    private int mActivatedPosition = ListView.INVALID_POSITION;

    public interface Callbacks {
        public void onItemSelected(String id);
    }

    private static Callbacks sContinentsCallbacks = new Callbacks() {
        @Override
        public void onItemSelected(String id) {
        }
    };

    public ContinentsListFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // TODO: replace with a real list adapter.
        setListAdapter(new ArrayAdapter<ContinentsContent.ContinentsItem>(
                getActivity(),
                android.R.layout.simple_list_item_activated_1,
                android.R.id.text1,
                ContinentsContent.ITEMS));
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        if (savedInstanceState != null
                && savedInstanceState.containsKey(STATE_ACTIVATED_POSITION)) {
            setActivatedPosition(savedInstanceState.getInt(STATE_ACTIVATED_POSITION));
        }
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);

        // Activities containing this fragment must implement its callbacks.
        if (!(activity instanceof Callbacks)) {
            throw new IllegalStateException("Activity must implement fragment's callbacks.");
        }

        mCallbacks = (Callbacks) activity;
    }

    @Override
    public void onDetach() {
        super.onDetach();

        // Reset the active callbacks interface to the Continents implementation.
        mCallbacks = sContinentsCallbacks;
    }

    @Override
    public void onListItemClick(ListView listView, View view, int position, long id) {
        super.onListItemClick(listView, view, position, id);

        mCallbacks.onItemSelected(ContinentsContent.ITEMS.get(position).id);
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        if (mActivatedPosition != ListView.INVALID_POSITION) {
            outState.putInt(STATE_ACTIVATED_POSITION, mActivatedPosition);
        }
    }

    public void setActivateOnItemClick(boolean activateOnItemClick) {
        getListView().setChoiceMode(activateOnItemClick
                ? ListView.CHOICE_MODE_SINGLE
                : ListView.CHOICE_MODE_NONE);
    }

    private void setActivatedPosition(int position) {
        if (position == ListView.INVALID_POSITION) {
            getListView().setItemChecked(mActivatedPosition, false);
        } else {
            getListView().setItemChecked(position, true);
        }

        mActivatedPosition = position;
    }
}

enter image description here

Answer 1

您的onAttach的实施，

if (!(activity instanceof Callbacks)) {
     throw new IllegalStateException("Activity must implement fragment's callbacks.");
}

要解决此问题，您必须将implements Callbacks添加到托管片段的Activity。

编辑：

在您的活动的xml中，替换

  <fragment android:id="@+id/continents_list" android:name="com.apptacularapps.md.ContinentsListFragment"
        android:layout_width="0dp" android:layout_height="match_parent" android:layout_weight="1"
        tools:layout="@android:layout/list_content" />

带

 <FrameLayout android:id="@+id/continents_list_contaniner" 
        android:layout_width="0dp" android:layout_height="match_parent" android:layout_weight="1"/>

在setContentView之后执行的

和onCreate（）：

FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.replace(R.id.continents_list_contaniner, new ContinentsListFragment());
ft.commit();

<强> EDIT2 ：

在您的活动替换

中

import android.app.FragmentManager;
import android.app.FragmentTransaction;

与

import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction

片段活动不膨胀

1 个答案: