无法解析AppCompatActivity中的findViewByID [英] Cannot resolve findViewByID in AppCompatActivity

问题描述

我正在关注本教程: Android使用标签进行材料设计

信息:

• Android API级别21
• 依赖项已添加到gradle文件 编译'com.android.support:appcompat-v7:23.0.1'和 编译'com.android.support:design:23.0.1' }

• Android API Level 21
• Dependecies are added to graddle file compile 'com.android.support:appcompat-v7:23.0.1' and compile 'com.android.support:design:23.0.1' }

无法解析方法"findViewById".我试图按照此答案无法解析Fragment中的方法'findViewById(int)'，但这AppCompatActivity使用OnCreateBundle代替OnCreateView，然后我无法获取View对象...

The method "findViewById" cannot be resolved. I tried to follow this answer Cannot resolve method 'findViewById(int)' in Fragment, but this AppCompatActivity use OnCreateBundle instead OnCreateView, then i can't get the View object...

此代码有什么问题?我缺少一些导入吗?

What is wrong with this code ? I'm missing some import?

    package info.androidhive.materialtabs.activity;

import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;

import java.util.ArrayList;
import java.util.List;

import info.androidhive.materialtabs.R;
import info.androidhive.materialtabs.fragments.OneFragment;
import info.androidhive.materialtabs.fragments.ThreeFragment;
import info.androidhive.materialtabs.fragments.TwoFragment;

public class MainActivity extends AppCompatActivity {

    private Toolbar toolbar;
    private TabLayout tabLayout;
    private ViewPager viewPager;

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

        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        viewPager = (ViewPager) findViewById(R.id.viewpager);
        setupViewPager(viewPager);

        tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);
    }

    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new OneFragment(), "ONE");
        adapter.addFragment(new TwoFragment(), "TWO");
        adapter.addFragment(new ThreeFragment(), "THREE");
        viewPager.setAdapter(adapter);
    }

    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }

        @Override
        public int getCount() {
            return mFragmentList.size();
        }

        public void addFragment(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }
    }
}

这是Android Studio显示的错误"，但我在logevent窗口中得到了0错误.

This is the "Error" that Android Studio show but i got 0 erros in logevent window

推荐答案

您似乎正在遇到Android Studio中损坏的缓存错误.

You appear to be running into the corrupt cache bug in Android Studio.

在使用自定义名称空间添加自定义视图时，这在我身上很多.如果您添加了任何自定义视图，则可能是您遇到的问题.

This happens to me a LOT when adding custom views with a custom namespace. If you added any custom views, this could be your issue.

要修复:文件>无效的缓存/重新启动

To fix: File > Invalidate Caches / Restart

这应该重新索引所有内容并允许自动完成工作，并且findViewById()也应该工作.我检查了代码，没有看到任何错误.

That should reindex everything and allow for auto-completion to work, as well, your findViewById() should work. I reviewed the code and do not see any errors.

这篇关于无法解析AppCompatActivity中的findViewByID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！