Question

所以我基本上创造了一个袋子，我被告知我的一个袋子必须包含至少100000个元素。这不适合eclipse的控制台窗口。因此，将信息写入文件似乎是一个更好的主意。我在这里放了我的main方法和runBigBad方法。正如您所看到的，在runBigBag之后，还有更多我想做的事情。它编译并运行良好。但是，它会在runBigBag（）调用后将所有内容打印到文本文件中。我只想在文本文件中使用runBigBag（）的内容，然后将其余内容打印到控制台窗口。有人可以帮我吗？当我尝试使用finally子句并执行ps.close（）时，它希望我初始化ps然后使文件为null。所以除非有更简单的方法，否则我不知道该怎么做。

public class TestBag {

public static <E> void main(String[] args) {
    //Start time for WHOLE PROGRAM
    final long start = System.currentTimeMillis();
    //Run small bag
    runSmallBag();
    //RESET COUNTERS TO ALLOW BIG BAG TO KEEP TRACK OF COMPLEXITY
    Bag.resetCounters();
    //Run big bag
    runBigBag();
    //Display the operation counters for each method used in whole program
    System.out.println("Number of times add() was used for whole program: " + Bag.addCountA + "\n");
    System.out.println("Number of times remRand() was used for whole program: " + Bag.ranRemCountA + "\n");
    System.out.println("Number of times rem() was used for whole program: " + Bag.remCountA + "\n");
    System.out.println("Number of times contains() was used whole program: " + Bag.containsCountA + "\n");
    System.out.println("number of times addAll() was used whole program: " + Bag.addAllCountA + "\n");
    System.out.println("Number of times union() was used whole program: " + Bag.unionCountA + "\n");
    System.out.println("Number of times equal() was used whole program: " + Bag.equalsCountA + "\n");
    //End timer for whole program
    final long end = System.currentTimeMillis();
    //Display timer for whole program
    System.out.println("The whole program took " + ((end - start)*.001) + " seconds to run");
}
public static <E> void runBigBag(){

    //Start time for big bag operations
    final long start2 = System.currentTimeMillis();

    boolean prog = true;

    //Create file to write bag too
    File file = new File("bag.txt");
    PrintStream ps;
    try {
        ps = new PrintStream(new FileOutputStream(file));
        System.setOut(ps);
    } catch (FileNotFoundException f) {
        f.printStackTrace();
    } finally
    //irrelevant code here


    //End timer for big bag
    final long end2 = System.currentTimeMillis();

    //Display timer for big bag
    System.out.println("This part of the program took " + ((end2 - start2)*.001) + " seconds to run");

}

}

Answer 1

使用setOut正在更改默认输出流，以便将所有后续system.out调用发送到文件编写器。如果您不希望发生这种情况，请不要使用默认输出流进行文件编写。

您问题的最快答案就在这里。 How do I create a file and write to it in Java?

Answer 2

虽然Tosh的回答对我来说可能更好，但我实际上发现了如何以我希望的方式做到这一点：

PrintStream ps;
PrintStream stdout = System.out;

我创建了另一个使用默认系统输出的PrintStream，在方法结束时，我输入了：

System.setOut(stdout);

我确信这可能会在我不想要的背景中做些什么，但是给了我需要的输出。谢谢你的建议@Tosh。

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2 个答案: