AsyncTask.java无法解析Nullable,Mainthread,WorkerThread的符号

时间:2018-04-08 21:14:33

标签: android android-asynctask android-appcompat android-annotations

我对android studio很新,但是我遇到了这个错误,我无法运行我的项目。我看到很多答案建议添加 support-annotations 依赖项,但我使用appcompat所以我不需要它。有什么想法吗?

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2 个答案:

答案 0 :(得分:0)

您是否拥有Android支持库?

要做到这一点,请将其添加到" app"的build.gradle文件中。模块:

dependencies {
    ...
    implementation "com.android.support:support-annotations:27.1.0"
}

然后同步项目。

有时您可以通过在错误消息上按Alt + Enter并选择解决方案来自动执行此操作。

答案 1 :(得分:0)

您需要获取包含导入内容的库,在模块的构建gradle文件中的依赖性标签内添加以下行:

//Determinant - Only square matrices have a determinant
template <typename T, std::size_t size>
T Determinant(Matrix<T, size, size> &mat)
{
    ASSERT(size >= 2, "Wtf? 1x1 matrix?")

    T determinant = {};

    //Base case - Smallest size of matrix we can calculate the determinant is 2x2
    if (size == 2)
    {
        return ((mat.m_data[0][0] * mat.m_data[1][1]) - (mat.m_data[0][1] * mat.m_data[1][0]));
    }
    else //otherwise, we need to grab the sub matrix within the current matrix and get the determinate of those. 
    {
        Matrix<T, size - 1, size -1 > subMatrix;

        //Note: We're filling in the new sub matrix column order
        for (int topRow_ColumnIndex = 0; topRow_ColumnIndex < size; ++topRow_ColumnIndex)
        {
            int newSubCol = 0;
            for (int subCol = 0; subCol < size; ++subCol)
            {
                int newSubRow = 0;

                if (subCol == topRow_ColumnIndex)
                {
                    continue;
                }

                //Sub matrices will start one row below the top row.
                for (int subRow = 1; subRow < size; ++subRow)
                {
                    subMatrix[newSubCol][newSubRow] = mat[subCol][subRow];
                    ++newSubRow;
                }
                ++newSubCol;
            }
            determinant = determinant + (T)pow(-1, topRow_ColumnIndex) * mat.m_data[topRow_ColumnIndex][0] *Determinant(subMatrix);
        }
    }
    return determinant;
}

Matrix<T, size - 1, size - 1 > subMatrix;

其中 X.X.X 是其余支持库的版本。

您应该阅读this article,其中详细介绍了如何实现此目的。