openRawResource无法通过ID找到资源的Kotlin Android问题

我是Kotlin新手，正在开发Android应用，尝试解析位于app/res/raw目录下的dataset.json文件，使用了如下代码：

import android.content.res.Resources

class FileHandler {

    fun getDataset(): String {
        return Resources.getSystem().openRawResource(R.raw.dataset).toString()
    }

}

但运行时抛出异常：

FATAL EXCEPTION: main
Process: com.example.yetanothertasktracker, PID: 11751
android.content.res.Resources$NotFoundException: Resource ID #0x7f090000
at android.content.res.ResourcesImpl.getValue(ResourcesImpl.java:276)
at android.content.res.ResourcesImpl.openRawResource(ResourcesImpl.java:404)
at android.content.res.Resources.openRawResource(Resources.java:1400)
at android.content.res.Resources.openRawResource(Resources.java:1344)
at com.example.yetanothertasktracker.FileHandler.<init>(FileHandler.kt:11)
at com.example.yetanothertasktracker.MainActivityKt.getTasksList(MainActivity.kt:31)
at com.example.yetanothertasktracker.ComposableSingletons$MainActivityKt$lambda-1$1.invoke(MainActivity.kt:22)
at com.example.yetanothertasktracker.ComposableSingletons$MainActivityKt$lambda-1$1.invoke(MainActivity.kt:21)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:109)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)
at androidx.compose.ui.platform.ComposeView.Content(ComposeView.android.kt:428)
at androidx.compose.ui.platform.AbstractComposeView$ensureCompositionCreated$1.invoke(ComposeView.android.kt:252)
at androidx.compose.ui.platform.AbstractComposeView$ensureCompositionCreated$1.invoke(ComposeView.android.kt:251)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:109)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)
at androidx.compose.runtime.CompositionLocalKt.CompositionLocalProvider(CompositionLocal.kt:228)
at androidx.compose.ui.platform.CompositionLocalsKt.ProvideCommonCompositionLocals(CompositionLocals.kt:186)
at androidx.compose.ui.platform.AndroidCompositionLocals_androidKt$ProvideAndroidCompositionLocals$3.invoke(AndroidCompositionLocals.android.kt:119)
at androidx.compose.ui.platform.AndroidCompositionLocals_androidKt$ProvideAndroidCompositionLocals$3.invoke(AndroidCompositionLocals.android.kt:118)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:109)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)
at androidx.compose.runtime.CompositionLocalKt.CompositionLocalProvider(CompositionLocal.kt:228)
at androidx.compose.ui.platform.AndroidCompositionLocals_androidKt.ProvideAndroidCompositionLocals(AndroidCompositionLocals.android.kt:110)
at androidx.compose.ui.platform.WrappedComposition$setContent$1$1$2.invoke(Wrapper.android.kt:139)
at androidx.compose.ui.platform.WrappedComposition$setContent$1$1$2.invoke(Wrapper.android.kt:138)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:109)
at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:35)
at androidx.compose.runtime.CompositionLocalKt.CompositionLocalProvider(CompositionLocal.kt:248)at androidx.compose.ui.platform.WrappedComposition$setContent$1$1.invoke(Wrapper.android.kt:138)

调试时发现R.raw.dataset能解析为整数ID，说明编译器能识别该资源，但传入openRawResource仍报错，直接传入该整数ID也同样异常，已尝试清理缓存并重启IDE，问题仍存在，请问我哪里操作有误？

核心错误原因 #

你使用了Resources.getSystem()获取Resources对象，这个对象仅能访问Android系统自带的资源，无法访问你的应用自己打包在res/raw下的资源，所以会抛出资源找不到的异常。

另外，原代码中直接调用openRawResource(...).toString()也不对，这只会返回输入流的对象描述字符串，不是文件的实际内容。

修复步骤 #

1. 传入应用的Context：通过Context获取当前应用的Resources对象，才能访问应用内的资源。
2. 正确读取输入流内容：将openRawResource返回的输入流转换成字符串。

修改后的FileHandler代码示例：

import android.content.Context
import java.io.BufferedReader
import java.io.InputStreamReader

class FileHandler(private val context: Context) {

    fun getDataset(): String {
        return try {
            val inputStream = context.resources.openRawResource(R.raw.dataset)
            val reader = BufferedReader(InputStreamReader(inputStream))
            val stringBuilder = StringBuilder()
            var line: String?
            while (reader.readLine().also { line = it } != null) {
                stringBuilder.append(line)
            }
            stringBuilder.toString()
        } catch (e: Exception) {
            e.printStackTrace()
            "" // 或者根据需求返回默认值
        }
    }
}

使用示例 #

在Activity或Composable中调用时，传入Context：

// 在Activity中
val fileHandler = FileHandler(this)
val dataset = fileHandler.getDataset()

// 在Composable中（通过LocalContext获取）
val context = LocalContext.current
val fileHandler = FileHandler(context)
val dataset = fileHandler.getDataset()

内容的提问来源于stack exchange，提问作者user29696570