java.lang.RuntimeException: Unable to resume activity {com.example.administrator.youji/com.example.administrator.youji.CameraActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.hardware.Camera.setPreviewDisplay(android.view.SurfaceHolder)' on a null object reference
先检查权限
权限没问题的话, 查看camera和holder的初始化的位置, 是否在调用的时候已经初始化完成