java - Android - IllegalStateException : cursor. getString(idx) 不能为空

Question

我已经按照这里的所有内容进行操作，但是为什么 cursor.getString(idx) 说它不能为 null？我提供了所有必要的参数..

这是我的getfilepath:

fun getFilePathFromUri(context: Context, imageURI: Uri): String? {

        var cursor : Cursor? = null
        var result: String

        try {
            val projection = arrayOf(MediaStore.Images.Media.DATA)

            cursor = context.contentResolver.query(imageURI, projection, null, null, null)

            if (cursor == null) {
                result = imageURI.path
            } else {
                Log.d(AppConstants.TAG, "Path_img = " + imageURI)
                Log.d(AppConstants.TAG, "Path_pth = " + imageURI.path)
                Log.d(AppConstants.TAG, "Path_cursor = " + cursor)

                cursor.moveToFirst()
                val idx = cursor.getColumnIndexOrThrow(MediaStore.Images.ImageColumns.DATA)
                result = cursor.getString(idx)
            }
            return result
        } finally {
                cursor!!.close()
        }
    }

这里是错误:

12-04 14:34:44.971 2008-2008/com.xxx.project k E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.xxx.proj, PID: 2008
    java.lang.IllegalStateException: cursor.getString(idx) must not be null
    at com.xxx.proj.utils.ImageUtils$Companion.getFilePathFromUri(ImageUtils.kt:78)
    at com.xxx.proj.api.Layer.createNewLayer(Layer.java:84)
    at com.xxx.proj.dialog.EventMapCreationDialog.registerNewMap(EventMapCreationDialog.kt:266)
    at com.xxx.proj.dialog.EventMapCreationDialog.onClick(EventMapCreationDialog.kt:82)
    at android.view.View.performClick(View.java:5204)
    at android.view.View$PerformClick.run(View.java:21153)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5417)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Answer 1

根据 documentation cursor.getString():

Returns the value of the requested column as a String.

The result and whether this method throws an exception when the column value is null or the column type is not a string type is implementation-defined.

您收到一个 IllegalStateException。虽然范围很广，但这通常意味着在错误/非法时间调用了一个方法。也就是说，应用程序或环境未处于适合此方法的状态。这可能意味着参数、游标或值为空。

调用方法前检查列的返回类型:

if (cursor.getType(idx) == FIELD_TYPE_STRING) {
    result = cursor.getString(idx);
}