安卓解决v4Error:Program type already present: android.support.v4.app.BackStackRecord

今天上课做项目时，出现如下错误，询问老师后解决了问题，在这里记录一下。

Error：Program type already present: android.support.v4.app.BackStackRecord

解决方法：打开 build.gradle
找到代码如下：

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'com.android.support:appcompat-v7:28.+'
    implementation 'com.android.support:support-v4:28.+'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation 'com.android.support:design:28.0.0'
    implementation 'com.github.lecho:hellocharts-library:1.5.8'
}

如上，在 implementation ‘com.android.support:appcompat-v7:28.+’ 下面加上依赖:

implementation 'com.android.support:support-v4:28.+'     (版本自定)

就可以了