java函数解密程序

Question

我对Java和编程都很在行这就是我学习它的原因：）我需要你的帮助来做一个练习。我需要在arg上做一些修改来创建函数破译器

import java.util.StringBuffer;

public class Decipherer{

    String arg ="aopi?sedohtém@#?sedhtmg+p9l!";

    int nbrChar = arg.length()/2;

    String arg2 = arg.substring(5, nbrChar-1);

    String arg3 = arg2.replace("@#?", " ");

    String arg4 = new StringBuilder(arg3).reverse().toString();

    return arg4;

}

public static void main(String[] args) {

    Decipherer mesage1 = new Decipherer("0@sn9sirppa@#?ia'jgtvryko1");
    Decipherer message3 = new Decipherer("q8e?wsellecif@#?sel@#?setuotpazdsy0*b9+mw@x1vj");
    Decipherer message4 = new Decipherer("aopi?sedohtém@#?sedhtmg+p9l!");

}

--

Exception in thread "main" java.lang.Error: Unresolved compilation problems: The constructor Decipherer(String) is undefined The constructor Decipherer(String) is undefined The constructor Decipherer(String) is undefined Syntax error, insert "}" to complete ClassBody

    at Decipherer.main(Decipherer.java:24)

我不明白为什么它会问另一个“}”。谁能给我解释一下吗

Answer 1

main方法必须在类中。你可以把它放在Decipherer。此外，您正在执行的操作必须放在一个方法中，以便能够返回某些内容。你需要一个接受String的构造函数，例如

public class Decipherer {

  private final String input;

  // constructor accepting String
  public Decipherer(String input) {
    this.input = input;
  }

  public String decipher() {

    int nbrChar = input.length() / 2;

    String arg2 = input.substring(5, nbrChar - 1);

    String arg3 = arg2.replace("@#?", " ");

    return new StringBuilder(arg3).reverse().toString();
  }

  // main method inside class
  public static void main(String[] args) {
    Decipherer decipherer1 = new Decipherer("0@sn9sirppa@#?ia'jgtvryko1");
    String message1 = decipherer1.decipher();
    Decipherer decipherer2 = new Decipherer("q8e?wsellecif@#?sel@#?setuotpazdsy0*b9+mw@x1vj");
    Decipherer decipherer3 = new Decipherer("aopi?sedohtém@#?sedhtmg+p9l!");
  }
}

通过执行new Decipherer("0@sn9sirppa@#?ia'jgtvryko1");，类型为Decipherer的对象将使用字段input创建。然后，您可以在这个对象上调用方法decipher()

或者，您也可以不使用构造函数，公开一个静态方法来解密，例如

public static String decipher(String input) {
    int nbrChar = input.length() / 2;
    String arg2 = input.substring(5, nbrChar - 1);
    String arg3 = arg2.replace("@#?", " ");
    return new StringBuilder(arg3).reverse().toString();
  }

您可以在主方法中调用它作为final String message = Decipherer.decipher("0@sn9sirppa@#?ia'jgtvryko1");