无法实例化片段，确保存在类名 [英] Unable to instantiate fragment make sure class name exists

问题描述

android.app.Fragment $ InstantiationException:无法实例化片段:确保类名存在，是公共的并且有一个空公共的构造函数.

android.app.Fragment$InstantiationException: Unable to instantiate fragment: make sure class name exists, is public, and has a empty constructor that is public.

我意识到有很多关于同一错误的问题，但是到目前为止，没有一个问题对我有帮助.我正在从一本书中学习，并且之前实际上已经运行过准确(99％正确)的代码.擦除所有内容并将其重写以供查看后，出现错误.

I realize there are many questions posted regarding the same error, but none have helped me so far. I am learning from a book, and have actually run the exact(99% sure) code before. After erasing it all and rewriting it for review, the error came up.

package com.paad.todolist;

import android.app.ListFragment;
import android.os.Bundle;

public class ToDoListFragment extends ListFragment{

    public static ToDoListFragment newInstance(int index) {
        ToDoListFragment f = new ToDoListFragment();

           Bundle args = new Bundle();
           args.putInt("index", index);
           f.setArguments(args);

           return f;
        }
    }

LogCat:

06-16 03:04:14.091:E/AndroidRuntime(836):致命异常:主要06-1603:04:14.091:E/AndroidRuntime(836):java.lang.RuntimeException:无法开始活动ComponentInfo {com.paad.todolist/com.paad.todolist.ToDoListActivity}:android.view.InflateException:二进制XML文件第13行:错误膨胀类片段06-16 03:04:14.091:E/AndroidRuntime(836):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)06-16 03:04:14.091:E/AndroidRuntime(836):atandroid.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)06-16 03:04:14.091:E/AndroidRuntime(836):atandroid.app.ActivityThread.access $ 600(ActivityThread.java:123)06-1603:04:14.091:E/AndroidRuntime(836):在android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1147)06-16 03:04:14.091:E/AndroidRuntime(836):atandroid.os.Handler.dispatchMessage(Handler.java:99)06-1603:04:14.091:E/AndroidRuntime(836):在android.os.Looper.loop(Looper.java:137)06-16 03:04:14.091:E/AndroidRuntime(836):位于android.app.ActivityThread.main(ActivityThread.java:4424)06-1603:04:14.091:E/AndroidRuntime(836):在java.lang.reflect.Method.invokeNative(本机方法)06-1603:04:14.091:E/AndroidRuntime(836):在java.lang.reflect.Method.invoke(Method.java:511)06-16 03:04:14.091:E/AndroidRuntime(836):位于com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:784)06-16 03:04:14.091:E/AndroidRuntime(836):atcom.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)06-1603:04:14.091:E/AndroidRuntime(836):在dalvik.system.NativeStart.main(本机方法)06-16 03:04:14.091:E/AndroidRuntime(836):原因:android.view.InflateException:二进制XML文件第13行:膨胀类片段06-16时出错03:04:14.091:E/AndroidRuntime(836):在android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:697)06-16 03:04:14.091:E/AndroidRuntime(836):atandroid.view.LayoutInflater.rInflate(LayoutInflater.java:739)06-1603:04:14.091:E/AndroidRuntime(836):在android.view.LayoutInflater.inflate(LayoutInflater.java:489)06-1603:04:14.091:E/AndroidRuntime(836):在android.view.LayoutInflater.inflate(LayoutInflater.java:396)06-1603:04:14.091:E/AndroidRuntime(836):在android.view.LayoutInflater.inflate(LayoutInflater.java:352)06-1603:04:14.091:E/AndroidRuntime(836):在com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:251)06-16 03:04:14.091:E/AndroidRuntime(836):atandroid.app.Activity.setContentView(Activity.java:1835)06-1603:04:14.091:E/AndroidRuntime(836):在com.paad.todolist.ToDoListActivity.onCreate(ToDoListActivity.java:18)06-16 03:04:14.091:E/AndroidRuntime(836):atandroid.app.Activity.performCreate(Activity.java:4466)06-1603:04:14.091:E/AndroidRuntime(836):在android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)06-16 03:04:14.091:E/AndroidRuntime(836):atandroid.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)06-16 03:04:14.091:E/AndroidRuntime(836):... 11更多06-1603:04:14.091:E/AndroidRuntime(836):原因:android.app.Fragment $ InstantiationException:无法实例化片段com.paad.todoList.ToDoListFragment:确保类名存在，是公共的，并且有一个空的构造函数，它是公共的06-1603:04:14.091:E/AndroidRuntime(836):在android.app.Fragment.instantiate(Fragment.java:585)06-1603:04:14.091:E/AndroidRuntime(836):在android.app.Fragment.instantiate(Fragment.java:549)06-1603:04:14.091:E/AndroidRuntime(836):在android.app.Activity.onCreateView(Activity.java:4235)06-1603:04:14.091:E/AndroidRuntime(836):在android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:673)06-16 03:04:14.091:E/AndroidRuntime(836):... 21更多06-1603:04:14.091:E/AndroidRuntime(836):原因:java.lang.ClassNotFoundException:com.paad.todoList.ToDoListFragment06-16 03:04:14.091:E/AndroidRuntime(836):atdalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)06-16 03:04:14.091:E/AndroidRuntime(836):atjava.lang.ClassLoader.loadClass(ClassLoader.java:501)06-1603:04:14.091:E/AndroidRuntime(836):在java.lang.ClassLoader.loadClass(ClassLoader.java:461)06-1603:04:14.091:E/AndroidRuntime(836):在android.app.Fragment.instantiate(Fragment.java:571)06-1603:04:14.091:E/AndroidRuntime(836):...还有24个

06-16 03:04:14.091: E/AndroidRuntime(836): FATAL EXCEPTION: main 06-16 03:04:14.091: E/AndroidRuntime(836): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.paad.todolist/com.paad.todolist.ToDoListActivity}: android.view.InflateException: Binary XML file line #13: Error inflating class fragment 06-16 03:04:14.091: E/AndroidRuntime(836): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.app.ActivityThread.access$600(ActivityThread.java:123) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.os.Handler.dispatchMessage(Handler.java:99) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.os.Looper.loop(Looper.java:137) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.app.ActivityThread.main(ActivityThread.java:4424) 06-16 03:04:14.091: E/AndroidRuntime(836): at java.lang.reflect.Method.invokeNative(Native Method) 06-16 03:04:14.091: E/AndroidRuntime(836): at java.lang.reflect.Method.invoke(Method.java:511) 06-16 03:04:14.091: E/AndroidRuntime(836): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 06-16 03:04:14.091: E/AndroidRuntime(836): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 06-16 03:04:14.091: E/AndroidRuntime(836): at dalvik.system.NativeStart.main(Native Method) 06-16 03:04:14.091: E/AndroidRuntime(836): Caused by: android.view.InflateException: Binary XML file line #13: Error inflating class fragment 06-16 03:04:14.091: E/AndroidRuntime(836): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:697) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.view.LayoutInflater.rInflate(LayoutInflater.java:739) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.view.LayoutInflater.inflate(LayoutInflater.java:489) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.view.LayoutInflater.inflate(LayoutInflater.java:396) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.view.LayoutInflater.inflate(LayoutInflater.java:352) 06-16 03:04:14.091: E/AndroidRuntime(836): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:251) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.app.Activity.setContentView(Activity.java:1835) 06-16 03:04:14.091: E/AndroidRuntime(836): at com.paad.todolist.ToDoListActivity.onCreate(ToDoListActivity.java:18) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.app.Activity.performCreate(Activity.java:4466) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920) 06-16 03:04:14.091: E/AndroidRuntime(836): ... 11 more 06-16 03:04:14.091: E/AndroidRuntime(836): Caused by: android.app.Fragment$InstantiationException: Unable to instantiate fragment com.paad.todoList.ToDoListFragment: make sure class name exists, is public, and has an empty constructor that is public 06-16 03:04:14.091: E/AndroidRuntime(836): at android.app.Fragment.instantiate(Fragment.java:585) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.app.Fragment.instantiate(Fragment.java:549) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.app.Activity.onCreateView(Activity.java:4235) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:673) 06-16 03:04:14.091: E/AndroidRuntime(836): ... 21 more 06-16 03:04:14.091: E/AndroidRuntime(836): Caused by: java.lang.ClassNotFoundException: com.paad.todoList.ToDoListFragment 06-16 03:04:14.091: E/AndroidRuntime(836): at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61) 06-16 03:04:14.091: E/AndroidRuntime(836): at java.lang.ClassLoader.loadClass(ClassLoader.java:501) 06-16 03:04:14.091: E/AndroidRuntime(836): at java.lang.ClassLoader.loadClass(ClassLoader.java:461) 06-16 03:04:14.091: E/AndroidRuntime(836): at android.app.Fragment.instantiate(Fragment.java:571) 06-16 03:04:14.091: E/AndroidRuntime(836): ... 24 more

推荐答案

发现，您的logcat说了一切

Found that, you logcat says everything

 Caused by: java.lang.ClassNotFoundException: com.paad.todoList.ToDoListFragment

您的包裹名称不正确.使用 com.paad.todolist 而不是 com.paad.todoList

Your package name is not correct. use com.paad.todolist instead of com.paad.todoList

这篇文章让我想起了电视节目对话框， Sherlock:您看到但看不到 :):)

This post reminds me the TV Show dialog, Sherlock : You see but you do not observe :) :)

这篇关于无法实例化片段，确保存在类名的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！