android - 如何解决应用程序已在 android studio 模拟器中停止（片段寻呼机适配器）

问题描述

我是 android 开发的初学者，在模拟器中运行我的应用程序时遇到了一些困难。我正在按照 head first 教科书的第 12 章来设计一个带有标签导航的应用程序。它有四个片段，我正在使用片段寻呼机适配器在应用程序中导航。当我在模拟器中运行应用程序时，它会因错误消息“应用程序已停止工作”而崩溃。我的主要活动代码如下：

package com.hfad.bitsandpizzas;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

import androidx.appcompat.widget.ShareActionProvider;
import androidx.appcompat.widget.Toolbar;
import androidx.core.view.MenuItemCompat;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentPagerAdapter;
import androidx.viewpager.widget.ViewPager;

public class MainActivity extends AppCompatActivity {

    private ShareActionProvider shareActionProvider;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        SectionsPagerAdapter pagerAdapter =
                new SectionsPagerAdapter(getSupportFragmentManager());
        ViewPager pager = (ViewPager) findViewById(R.id.pager);
        pager.setAdapter(pagerAdapter);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        MenuItem menuItem = menu.findItem(R.id.action_share);
        shareActionProvider =
                (ShareActionProvider) MenuItemCompat.getActionProvider(menuItem);
        setShareActionIntent("Want to join me for pizza?");
        return super.onCreateOptionsMenu(menu);
    }

    private void setShareActionIntent(String text) {
        Intent intent = new Intent(Intent.ACTION_SEND);
        intent.setType("text/plain");
        intent.putExtra(Intent.EXTRA_TEXT, text);
        shareActionProvider.setShareIntent(intent);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.action_create_order:
                Intent intent = new Intent(this, OrderActivity.class);
                startActivity(intent);
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

    private class SectionsPagerAdapter extends FragmentPagerAdapter {
        public SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }
        @Override
        public int getCount() {
            return 4;
        }
        @Override
        public Fragment getItem(int position) {
            switch (position) {
                case 0:
                    return new TopFragment();
                case 1:
                    return new PizzaFragment();
                case 2:
                    return new PastaFragment();
                case 3:
                    return new StoresFragment();
            }
            return null;
        }
    }
}

来自 logcat 的错误消息是这样的

2020-06-04 15:10:08.263 11458-11458/com.hfad.bitsandpizzas E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.hfad.bitsandpizzas, PID: 11458
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.hfad.bitsandpizzas/com.hfad.bitsandpizzas.MainActivity}: android.view.InflateException: Binary XML file line #14: Binary XML file line #14: Error inflating class android.support.v4.view.ViewPager
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
        at android.app.ActivityThread.-wrap12(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6119)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
     Caused by: android.view.InflateException: Binary XML file line #14: Binary XML file line #14: Error inflating class android.support.v4.view.ViewPager
     Caused by: android.view.InflateException: Binary XML file line #14: Error inflating class android.support.v4.view.ViewPager
     Caused by: java.lang.ClassNotFoundException: Didn't find class "android.support.v4.view.ViewPager" on path: DexPathList[[zip file "/data/app/com.hfad.bitsandpizzas-1/base.apk"],nativeLibraryDirectories=[/data/app/com.hfad.bitsandpizzas-1/lib/x86, /system/lib, /vendor/lib]]
        at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:380)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
        at android.view.LayoutInflater.createView(LayoutInflater.java:609)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:787)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:858)
        at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:821)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:518)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:426)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:377)
        at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:555)
        at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:161)
        at com.hfad.bitsandpizzas.MainActivity.onCreate(MainActivity.java:25)
        at android.app.Activity.performCreate(Activity.java:6679)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
        at android.app.ActivityThread.-wrap12(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6119)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

标签： androidandroid-fragments

android - 如何解决应用程序已在 android studio 模拟器中停止（片段寻呼机适配器）

问题描述

解决方案

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