Android Compose项目构建后出现未解析引用错误求助

问题背景 #

跟随Android Developers官方课程创建新项目，构建后出现多个Compose组件未解析引用错误。

相关代码 #

MainActivity.kt #

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Surface
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.tooling.preview.Preview
import com.junclabs.diceroller.ui.theme.DiceRollerTheme

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            DiceRollerTheme {
                // A surface container using the 'background' color from the theme
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colorScheme.background
                ) {
                    DiceRollerApp()
                }
            }
        }
    }
}

@Preview
@Composable
fun DiceRollerApp() {
    DiceWithButtonAndImage(
        modifier = Modifier
            .fillMaxSize()
            .wrapContentSize(Alignment.Center)
    )
}

@Composable
fun DiceWithButtonAndImage(
    modifier: Modifier = Modifier
) {
    var result by remember { mutableStateOf(1) }
    Column(modifier = modifier, horizontalAlignment = CenterHorizontally) {
        Image(painter = painterResource(id = imageResource), contentDescription = result.toString())
        val imageResource =
            when (result) {
                1 -> R.drawable.dice_1
                2 -> R.drawable.dice_2
                3 -> R.drawable.dice_3
                4 -> R.drawable.dice_4
                5 -> R.drawable.dice_5
                else -> R.drawable.dice_6
            }
        Spacer(modifier = Modifier.height(16.dp))
        Button(onClick = { result = (1..6).random() }) {
            Text(stringResource(R.string.roll))
        }
    }
}

build.gradle.kts (:app) #

plugins {
    id("com.android.application")
    id("org.jetbrains.kotlin.android")
}

android {
    namespace = "com.junclabs.diceroller"
    compileSdk = 34

    defaultConfig {
        applicationId = "com.junclabs.diceroller"
        minSdk = 25
        targetSdk = 34
        versionCode = 1
        versionName = "1.0"

        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
        vectorDrawables {
            useSupportLibrary = true
        }
    }

    buildTypes {
        release {
            isMinifyEnabled = false
            proguardFiles(
                getDefaultProguardFile("proguard-android-optimize.txt"),
                "proguard-rules.pro"
            )
        }
    }
    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_1_8
        targetCompatibility = JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = "1.8"
    }
    buildFeatures {
        compose = true
    }
    composeOptions {
        kotlinCompilerExtensionVersion = "1.5.1"
    }
    packaging {
        resources {
            excludes += "/META-INF/{AL2.0,LGPL2.1}"
        }
    }
}

dependencies {

    implementation("androidx.core:core-ktx:1.12.0")
    implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.7.0")
    implementation("androidx.activity:activity-compose:1.8.2")
    implementation(platform("androidx.compose:compose-bom:2023.08.00"))
    implementation("androidx.compose.ui:ui:1.5.4")
    implementation("androidx.compose.ui:ui-graphics:1.5.4")
    implementation("androidx.compose.ui:ui-tooling-preview:1.5.4")
    implementation("androidx.compose.material3:material3:1.1.2")
    testImplementation("junit:junit:4.13.2")
    androidTestImplementation("androidx.test.ext:junit:1.1.5")
    androidTestImplementation("androidx.test.espresso:espresso-core:3.5.1")
    androidTestImplementation(platform("androidx.compose:compose-bom:2023.08.00"))
    androidTestImplementation("androidx.compose.ui:ui-test-junit4")
    debugImplementation("androidx.compose.ui:ui-tooling")
    debugImplementation("androidx.compose.ui:ui-test-manifest")
}

错误说明 #

截图显示以下未解析引用：remember、mutableStateOf、Column、Alignment、Image、painterResource、Spacer、Button、Text、stringResource、imageResource以及R类相关引用。

解决方案 #

1. 补充缺失的导入语句 #

在MainActivity.kt顶部添加以下导入：

import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.wrapContentSize
import androidx.compose.material3.Button
import androidx.compose.material3.Text
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.res.painterResource
import androidx.compose.ui.res.stringResource
import androidx.compose.ui.unit.dp
import com.junclabs.diceroller.R

2. 调整变量声明顺序 #

将imageResource的定义移到Image组件之前，确保使用时变量已初始化：

@Composable
fun DiceWithButtonAndImage(
    modifier: Modifier = Modifier
) {
    var result by remember { mutableStateOf(1) }
    // 先声明imageResource再使用
    val imageResource =
        when (result) {
            1 -> R.drawable.dice_1
            2 -> R.drawable.dice_2
            3 -> R.drawable.dice_3
            4 -> R.drawable.dice_4
            5 -> R.drawable.dice_5
            else -> R.drawable.dice_6
        }
    Column(modifier = modifier, horizontalAlignment = CenterHorizontally) {
        Image(painter = painterResource(id = imageResource), contentDescription = result.toString())
        Spacer(modifier = Modifier.height(16.dp))
        Button(onClick = { result = (1..6).random() }) {
            Text(stringResource(R.string.roll))
        }
    }
}

3. 同步并重建项目 #

• 执行File -> Sync Project with Gradle Files同步Gradle配置
• 执行Build -> Clean Project清理旧构建文件
• 执行Build -> Rebuild Project重新构建项目

内容的提问来源于stack exchange，提问作者Juncu