相关疑难解决方法(0)

我正在使用Android Lollipop(5.0)中使用的新Material Design创建一个应用程序.

我使用以下指南:

• http://android-developers.blogspot.it/2014/10/appcompat-v21-material-design-for-pre.html
• http://antonioleiva.com/material-design-everywhere/

创建工具栏后,我收到此错误:"以下类无法实例化: - android.support.v7.widget.Toolbar"

该应用程序在手机或模拟器中运行良好,但Android Studio的布局设计器无法正确显示布局.

这里有一些图片:

my_awesome_toolbar.xml布局预览中出错

activity_my.xml布局预览出错

文件的xml代码:

my_awesome_toolbar.xml:

<?xml version="1.0" encoding="utf-8"?>

<android.support.v7.widget.Toolbar
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/my_awesome_toolbar"
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:minHeight="?attr/actionBarSize"
android:background="?attr/colorPrimary" />

activity_my.xml:

<RelativeLayout 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:id="@+id/root"
            tools:context="com.myapp.test.MyActivity"
            android:orientation="horizontal">

    <include
        android:id="@+id/toolbar"
        layout="@layout/my_awesome_toolbar"
        />
    <!-- Rest of layout -->
</RelativeLayout>

MyActivity.java:

package com.myapp.test;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;


public class MyActivity extends ActionBarActivity {

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

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

我有一个正在运行的项目,所有的xml文件都显示错误消息Android Failed to instantiate one or more classes.该计划仍然有效.

我清理了缓存并使用了无效的缓存和重启.

这里的完整信息:

以下类无法实例化android.support.v7.widget.AppCompatTextView

提示:在自定义视图中使用View.isInEditMode()可以在IDE中显示时跳过代码或显示示例数据.

java.lang.NullPointerException
    at android.content.res.Resources_Delegate.getValue(Resources_Delegate.java:788)
    at android.content.res.Resources.getValue(Resources.java:1286)
    at android.support.v4.content.res.ResourcesCompat.loadFont(ResourcesCompat.java:212)
    at android.support.v4.content.res.ResourcesCompat.getFont(ResourcesCompat.java:206)
    at android.support.v7.widget.TintTypedArray.getFont(TintTypedArray.java:119)
    at android.support.v7.widget.AppCompatTextHelper.updateTypefaceAndStyle(AppCompatTextHelper.java:208)
    at android.support.v7.widget.AppCompatTextHelper.loadFromAttributes(AppCompatTextHelper.java:152)
    at android.support.v7.widget.AppCompatTextHelperV17.loadFromAttributes(AppCompatTextHelperV17.java:38)
    at android.support.v7.widget.AppCompatTextView.<init>(AppCompatTextView.java:81)
    at android.support.v7.widget.AppCompatTextView.<init>(AppCompatTextView.java:71)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at org.jetbrains.android.uipreview.ViewLoader.createNewInstance(ViewLoader.java:475)
    at org.jetbrains.android.uipreview.ViewLoader.loadClass(ViewLoader.java:250)
    at org.jetbrains.android.uipreview.ViewLoader.loadClass(ViewLoader.java:213)
    at com.android.tools.idea.rendering.LayoutlibCallbackImpl.loadClass(LayoutlibCallbackImpl.java:193)
    at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:333)
    at android.view.BridgeInflater.onCreateView(BridgeInflater.java:152)
    at android.view.LayoutInflater.onCreateView(LayoutInflater.java:717)
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:785)
    at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:222)
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727)
    at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:858)
    at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:70)
    at android.view.LayoutInflater.rInflate(LayoutInflater.java:834)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
    at com.android.layoutlib.bridge.bars.CustomBar.<init>(CustomBar.java:95)
    at com.android.layoutlib.bridge.bars.StatusBar.<init>(StatusBar.java:67)
    at com.android.layoutlib.bridge.impl.Layout.createStatusBar(Layout.java:224)
    at com.android.layoutlib.bridge.impl.Layout.<init>(Layout.java:146) …

注意:我已经完成了所有相关的帖子并完成了所写的内容,但没有任何效果.

我试图ConstraintLayout为百分比尺寸添加1.1.0-beta1,但每当我这样做时,底部会出现一个弹出窗口.


我多次点击"安装存储库和同步项目"但没有任何反应.所以,我尝试在Build.gradle(Project)中添加以下代码,它工作正常,但出现了新的错误.

repositories {
    maven {
        url 'https://maven.google.com'
    }
}

新的错误与 AppCompatTextView

无法实例化以下类: - android.support.v7.widget.AppCompatTextView

java.lang.NullPointerException
    at android.content.res.Resources_Delegate.getValue(Resources_Delegate.java:788)
    at android.content.res.Resources.getValue(Resources.java:1286)
    at android.support.v4.content.res.ResourcesCompat.loadFont(ResourcesCompat.java:212)
    at android.support.v4.content.res.ResourcesCompat.getFont(ResourcesCompat.java:206)
    at android.support.v7.widget.TintTypedArray.getFont(TintTypedArray.java:119)
    at android.support.v7.widget.AppCompatTextHelper.updateTypefaceAndStyle(AppCompatTextHelper.java:208)
    at android.support.v7.widget.AppCompatTextHelper.loadFromAttributes(AppCompatTextHelper.java:152)
    at android.support.v7.widget.AppCompatTextHelperV17.loadFromAttributes(AppCompatTextHelperV17.java:38)
    at android.support.v7.widget.AppCompatTextView.<init>(AppCompatTextView.java:81)
    at android.support.v7.widget.AppCompatTextView.<init>(AppCompatTextView.java:71)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at org.jetbrains.android.uipreview.ViewLoader.createNewInstance(ViewLoader.java:475)
    at org.jetbrains.android.uipreview.ViewLoader.loadClass(ViewLoader.java:250)
    at org.jetbrains.android.uipreview.ViewLoader.loadClass(ViewLoader.java:213)
    at com.android.tools.idea.rendering.LayoutlibCallbackImpl.loadClass(LayoutlibCallbackImpl.java:193)
    at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:333)
    at android.view.BridgeInflater.onCreateView(BridgeInflater.java:152)
    at android.view.LayoutInflater.onCreateView(LayoutInflater.java:717)
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:785)
    at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:222)
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727)
    at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:858)
    at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:70)
    at android.view.LayoutInflater.rInflate(LayoutInflater.java:834)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
    at com.android.layoutlib.bridge.bars.CustomBar.<init>(CustomBar.java:95) …