Java 如何修复Android Studio中的“缺少类”错误?
当我尝试在Android Studio中进行新活动时 这些错误都会发生,在此错误之前,我创建了一些活动,通常没有任何错误:Java 如何修复Android Studio中的“缺少类”错误?,java,android,xml,Java,Android,Xml,当我尝试在Android Studio中进行新活动时 这些错误都会发生,在此错误之前,我创建了一些活动,通常没有任何错误: The following classes could not be found: - android.support.constraint.ConstraintLayout ( Add constraint-layout library dependency to the project, Fix Build Path, Edit XML, Create Class
The following classes could not be found:
- android.support.constraint.ConstraintLayout ( Add constraint-layout library dependency to the project, Fix Build Path, Edit XML, Create Class)
- android.support.design.widget.CoordinatorLayout (Fix Build Path, Edit XML, Create Class)
- android.support.v7.widget.Toolbar (Fix Build Path, Edit XML, Create Class)
依赖项库:
dependencies {
implementation fileTree(include: ['*.jar'], dir: 'libs')
implementation 'androidx.appcompat:appcompat:1.0.2'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
implementation 'com.android.support:support-v4:29.+'
implementation 'com.android.support:design:29.+'
implementation 'com.android.support:appcompat-v7:29.+'
implementation 'com.android.support.constraint:constraint-layout:1.1.3'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'androidx.test:runner:1.2.0'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
implementation 'com.google.android.material:material:1.0.0'
implementation 'com.squareup.retrofit2:retrofit:2.0.2'
implementation 'com.squareup.retrofit2:converter-gson:2.0.2'
implementation 'com.squareup.picasso:picasso:2.5.2'
implementation 'de.hdodenhof:circleimageview:3.0.0'
implementation 'com.mikhaellopez:circularimageview:3.2.0'
implementation 'com.google.android.gms:play-services-base:11.0.1'
implementation 'com.google.android.gms:play-services-basement:11.0.1'
implementation 'com.google.android.gms:play-services-safetynet:11.0.1'
implementation 'com.google.android.gms:play-services-tasks:11.0.1'
}
看起来您正在尝试在同一项目中使用AndroidX库和支持库。从菜单迁移到AndroidX,它将替换包名和依赖项 您的项目正在添加来自支持库的小部件,而不是导致此问题的AndroidX 如果仍然出现错误,请替换列表中的旧包名称: 您将AndroidX依赖项与AppCompat混为一谈。要么从重构->迁移到AndroidX将其迁移到AndroidX,要么使用AppCompat 正如在代码中一样,您已经对约束布局使用了这两个依赖项。解决您的问题的最简单方法是删除该行
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
在这里发布您的依赖项库代码。编辑第一篇文章您有AndroidX项目,并且您说您创建的活动没有任何错误,所以请检查这些活动:android.support.constraint.ConstraintLayout,android.support.design.widget.CoordinatorLayout,android.support.v7.widget.Toolbar…并将其转换为androidx dependency。@Niklaus转到laylut文件,将约束布局的包名替换为androidx.widget.constraintLayout