JavaCompiler:是否可以在运行时输入变量

时间:2012-07-19 17:00:11

标签: java compiler-construction javac

我将不得不在不久的将来使用JavaCompilers,所以我现在正在努力学习基础知识并选择最好的学习方法,并且我遇到了一个问题,我无法在网上找到答案

目前我正在查看JavaCompiler。如果我正在评估程序X并从System.in获取输入并将输出打印到System.out, 我可以编译并运行它,同时输入一些特定的输入并在文件中捕获它的输出吗?

如果是这样,网上是否有任何示例,我可以尝试更好地理解它?

编辑:

编译时传入的简单测试用例

import java.util.Iterator;

public class TestSet
{
public static void main(String[] args)
{
  try
  {
     System.out.print(   "[1]--constructor 1, size, isEmpty: ");
     LinkedSet<String> s1 = new LinkedSet<String>();
     if (s1.size() != 0)
        System.out.print("*** size? ***");
     if (!s1.isEmpty())
        System.out.print("*** isEmpty? ***");
     System.out.println();
  }
  catch(Exception e)
  {
     System.out.println("*** CRASH !!! ***");
  }
  try
  {
     System.out.print(   "[2]--constructor 2, size, isEmpty: ");
     LinkedSet<String> s1 = new LinkedSet<String>( "alpha");
     if (s1.size() != 1)
        System.out.print("*** size? ***");
     if (s1.isEmpty())
        System.out.print("*** isEmpty? ***");
     System.out.println();
  }
  catch(Exception e)
  {
     System.out.println("*** CRASH !!! ***");
  }
  try
  {
     System.out.print(   "[3]--contains: ");
     LinkedSet<String> s1 = new LinkedSet<String>("alpha");
     if (!s1.contains("alpha"))
        System.out.print("*** elt. not found ***");
     if (s1.contains("beta"))
        System.out.print("*** non-elt ``found'' ***");
     System.out.println();
  }
  catch(Exception e)
  {
     System.out.println("*** CRASH !!! ***");
  }
  try
  {
     System.out.print(   "[4]--add: ");
     LinkedSet<String> s1 = new LinkedSet<String>();
     s1.add("alpha");
     s1.add("beta");
     s1.add("gamma");
     if (s1.size() != 3)
        System.out.print("*** size? ***");
     if (!s1.contains("alpha") ||
        !s1.contains("beta") ||
        !s1.contains("gamma"))
        System.out.print("*** elt. not found ***");
     if (s1.contains("delta"))
        System.out.print("*** non-elt ``found'' ***");
     s1.add("beta");
     if (s1.size() != 3)
        System.out.print("*** size/duplicates? ***");
     System.out.println();
  }
  catch(Exception e)
  {
     System.out.println("*** CRASH !!! ***");
  }
  try
  {
     System.out.print(   "[5]--remove: ");
     LinkedSet<String> s1 = new LinkedSet<String>();
     s1.add("alpha");
     s1.add("beta");
     s1.add("gamma");
     s1.remove("beta");
     s1.remove("alpha");
     s1.remove("gamma");
     if (s1.size() != 0)
        System.out.print("*** size? ***");
     if (s1.contains("alpha") ||
        s1.contains("beta") ||
        s1.contains("gamma"))
        System.out.print("*** non elt. ``found'' ***");
     System.out.println();
  }
  catch(Exception e)
  {
     System.out.println("*** CRASH !!! ***");
  }
  try
  {
     System.out.print(   "[6]--print: ");
     LinkedSet<String> s1 = new LinkedSet<String>();
     s1.add("this");
     s1.add("is");
     s1.add("assignment");
     s1.add("four");
     s1.print();
  }
  catch(Exception e)
  {
     System.out.println("*** CRASH !!! ***");
  }
  try
  {
     System.out.print(   "[7]--addAll: ");
     LinkedSet<String> s1 = new LinkedSet<String>();
     s1.add("alpha");
     s1.add("beta");
     s1.add("gamma");
     LinkedSet<String> s2 = new LinkedSet<String>();
     s2.add("beta");
     s2.add("delta");
     s1.addAll(s2);
     if (!s1.contains("alpha") || ! s1.contains("beta") ||
        !s1.contains("gamma") || !s1.contains("delta"))
        System.out.print("*** elt. ``dropped'' ***");
     if (s1.size() != 4)
        System.out.print("*** size ? ***");
     System.out.println();
  }
  catch(Exception e)
  {
     System.out.println("*** CRASH !!! ***");
  }

  try
  {
     System.out.print(   "[8]--containsAll: ");
     LinkedSet<String> s1 = new LinkedSet<String>();
     s1.add("alpha");
     s1.add("beta");
     s1.add("gamma");
     LinkedSet<String> s2 = new LinkedSet<String>();
     s2.add("beta");
     s2.add("delta");
     if (s1.containsAll(s2))
        System.out.print("*** non-containment incorrect ***");
     LinkedSet<String> s3 = new LinkedSet<String>();
     s3.add("beta");
     s3.add("alpha");
     if (!s1.containsAll(s3))
        System.out.print("*** containment incorrect ***");
     System.out.println();
  }
  catch(Exception e)
  {
     System.out.println("*** CRASH !!! ***");
  }
  try
  {
     System.out.print(   "[9]--removeAll: ");
     LinkedSet<String> s1 = new LinkedSet<String>();
     s1.add("alpha");
     s1.add("beta");
     s1.add("gamma");
     s1.add("delta");
     LinkedSet<String> s2 = new LinkedSet<String>();
     s2.add("beta");
     s2.add("delta");
     s1.removeAll(s2);
     if (s1.contains("beta") || s1.contains("delta"))
        System.out.print("*** some  elts not removed? ***");
     if (!s1.contains("alpha") || !s1.contains("gamma"))
        System.out.print("*** wrong elts removed? ***");
     System.out.println();
  }
  catch(Exception e)
  {
     System.out.println("*** CRASH !!! ***");
  }
  try
  {
     System.out.print(   "[10]--retainAll: ");
     LinkedSet<String> s1 = new LinkedSet<String>();
     s1.add("alpha");
     s1.add("beta");
     s1.add("gamma");
     s1.add("delta");
     LinkedSet<String> s2 = new LinkedSet<String>();
     s2.add("beta");
     s2.add("delta");
     s1.retainAll(s2);
     if (s1.contains("alpha") || s1.contains("gamma"))
        System.out.print("*** wrong elts retained? ***");
     if (!s1.contains("beta") || !s1.contains("delta"))
        System.out.print("*** wrong elts removed? ***");
     System.out.println();
  }
  catch(Exception e)
  {
     System.out.println("*** CRASH !!! ***");
  }
  try
  {
     System.out.print(   "[11]--elements: ");
     LinkedSet<String> s1 = new LinkedSet<String>();
     s1.add("alpha");
     s1.add("beta");
     s1.add("gamma");
     s1.add("delta");
     Iterator<String> list = s1.elements();
     System.out.print("("+list.hasNext()+") ");
     if (list.hasNext())
        System.out.print(list.next()+"; ");
     System.out.print("("+list.hasNext()+")");
     if (list.hasNext())
        System.out.print(list.next()+"; ");
     System.out.print("("+list.hasNext()+")");
     if (list.hasNext())
        System.out.print(list.next()+"; ");
     System.out.print("("+list.hasNext()+")");
     if (list.hasNext())
        System.out.print(list.next()+"; ");
     System.out.print("("+list.hasNext()+")");
     if (list.hasNext())
        System.out.print(list.next()+"; ");   
     System.out.println();
  }
  catch(Exception e)
  {
     System.out.println("*** CRASH !!! ***");
  }
}
}

2 个答案:

答案 0 :(得分:1)

这不是一个编译器问题。我很确定你想要的只是输入/输出重定向,可能只需要一些脚本。

基础知识是:

  • 您可以使用<字符
  • 将文本文件用作程序的输入
  • 您可以使用>字符
  • 将文本文件用作程序的输出

例如,如果我在Foo.java中有一个程序,并且我想从in.txt给它输入,将其结果存储在out.txt中,我可能会输入:

javac Foo.java
java Foo <in.txt >out.txt

在Foo运行之后,out.txt会将Foo打印到System.out。有关文本输入和输出的更多信息,请查看shell文档。

答案 1 :(得分:1)

雅你可以......

1。您是在谈论命令行参数,如果是,那么它可能就是......

<强>例如

javac Test.java
enter code herejava Test Hello       // Hello is the Input

在Java中,“Hello”输入被发送到其中的main()方法String [] array

public static void main(String[] args)

因此,要访问作为Hello方法参数的参数传递的main(),您需要执行此操作。

 String s = args[0];

2. 现在,如果你想在程序内部将其写入文件,请执行此操作。

 String s = args[0];
 File f = new File(d:\\vivek.txt);
 FileWriter fw = new FileWriter(f);
 BufferedWriter bw = new BufferedWriter(fw);

 bw.write(s);