android - 赋值不是表达式 - Kotlin

Question

我正在将我用 Java 构建的项目重构为 Kotlin，并从 sqlite Assets 表复制数据库我正在这样做，它工作正常。

private void copyDataBase() throws IOException {
        InputStream mInput = mContext.getAssets().open(DB_NAME);
        String outFileName = DB_PATH + DB_NAME;
        OutputStream mOutput = new FileOutputStream(outFileName);
        byte[] mBuffer = new byte[1024];
        int mLength;
        while ((mLength = mInput.read(mBuffer)) > 0) {
            mOutput.write(mBuffer, 0, mLength);
        }
        mOutput.flush();
        mOutput.close();
        mInput.close();
    }

如何处理“赋值不是表达式，在此上下文中只允许使用表达式”？

@Throws(IOException::class)
    private fun copyDataBase() {
        val mInput = mContext.assets.open(DB_NAME)
        val outFileName = DB_PATH + DB_NAME
        val mOutput = FileOutputStream(outFileName)
        val mBuffer = ByteArray(1024)
        var mLength: Int
        while ((mLength = mInput.read(mBuffer)) > 0) {
            mOutput.write(mBuffer, 0, mLength)
        }
        mOutput.flush()
        mOutput.close()
        mInput.close()
    }

错误在这里

while ((mLength = mInput.read(mBuffer)) > 0) {
            mOutput.write(mBuffer, 0, mLength)
        }

谢谢。

Answer 1

将其更改为:

 mLength = mInput.read(mBuffer)
 while (mLength > 0) { 
        mOutput.write(mBuffer, 0, mLength)
        mLength = mInput.read(mBuffer)
    }