Question

我正在寻找一种方法将代码块传递给方法，然后该方法将对传递给方法的其他参数执行操作，获取这些操作的结果，并将这些结果传递给传递给方法的代码块。为清楚起见：

private static void method1(String filename, int sheetNum) {
    runOnSheet(filename, () -> {
        doStuffWithStream(FileInputStream fileStream);         // Does something with a file stream
        doOtherStuffWithStream(FileInputStream fileStream);    // Does something else with a file stream
    });
}

// Elsewhere
private static void runOnFile(String fileName, Runnable block1) {
    try {
        fileStream = new FileInputStream(fileName);
    } catch (IOException e) {
        e.printStackTrace();
    }

    block1.run();    // I'd like to pass fileStream to this code block. Ideally i could do block1.run(fileStream );

    fileStream.close();
}

我希望能够在任何需要打开文件的地方重用runOnFile，在流上运行一些代码并关闭流。
我真正想要做的是更复杂，除了FileInputStream之外还使用其他库，但我希望实现的结构是相同的。

感谢您的帮助！

Answer 1

Java 8+有一个名为private static void method1(String filename, int sheetNum) { runOnFile(filename, (fileStream) -> { doStuffWithStream(fileStream); doOtherStuffWithStream(fileStream); }); } // Elsewhere private static void runOnFile(String fileName, Consumer<FileInputStream> block1) { try { fileStream = new FileInputStream(fileName); } catch (IOException e) { e.printStackTrace(); } block1.accept(fileStrean); fileStream.close(); }的类，可用于您的用例： customize

try-with-resource

编辑：正如Dimitri使用// Elsewhere private static void runOnFile(String fileName, Consumer<FileInputStream> block1) { try (FileInputStream fis = new FileInputStream(fileName)) { block1.accept(fis); } catch (IOException e) { e.printStackTrace(); } }语法所建议的那样：

assetlinks.json

Answer 2

尝试这样的事情：

private static void method1(String filename, int sheetNum)
{
  try ( final FileInputStream fileStream = new FileInputStream(filename))
  {
    runOnSheet(filename, () -> 
    {
      doStuffWithStream(fileStream);         // Does something with a file stream
      doOtherStuffWithStream(fileStream);    // Does something else with a file stream
    });
  }
}

通过Lambda采取参数方法

2 个答案: