-5

所以我写了一个 JAVA 代码，它应该告诉用户如果组合其他两种（从列表中）随机选择的颜色，他会得到什么颜色。请注意，我对 JAVA 很陌生（以前只用 Python 编程过）。

代码：

    package ListOfWords;

     public class testListWords {
  public static void main (String[] args) {

      String [] colors = {"red","green","gray","black","blue","yellow"};

      int colorsLength = colors.length;

      int rand1 = (int) (Math.random() * colorsLength);
      int rand2 = (int) (Math.random() * colorsLength);

      while(rand1==rand2){
          int rand2 = (int) (Math.random() * colorsLength);
      }

      String phrase1 = colors[rand1];
      String phrase2 = colors[rand2];       

      while(phrase1 = "green"){

       if (phrase2 = "red") {
          System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Brown");
        }
       if (phrase2 = "gray") {
          System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Dark Green");
        }
       if (phrase2 = "black") {
          System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Black");
        }
        if (phrase2 = "blue") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Brown");
        }

        if (phrase2 = "yellow") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Brown");
        }
        }
    while(phrase1 = "red"){

        if (phrase2 = "green") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Brown");
        }
        if (phrase2 = "gray") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Dark Red");
        }
        if (phrase2 = "black") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Black");
        }
        if (phrase2 = "blue") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Brown");
        }
        if (phrase2 = "yellow") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Brown");
        }
     }
     while(phrase1 = "gray"){

        if (phrase2 = "red") {
        System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Dark red");
        }
        if (phrase2 = "green") {
        System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Dark Green");
        }
        if (phrase2 = "black") {
        System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Black");
        }
        if (phrase2 = "blue") {
        System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the Dark blue");
        }
        if (phrase2 = "yellow") {
        System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Green");
        }
     }
     while(phrase1 = "black"){

        if (phrase2 = "red") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Black");
        }
        if (phrase2 = "green") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Black");
        }
        if (phrase2 = "gray") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Black");
        }
        if (phrase2 = "blue") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the Black");
        }
        if (phrase2 = "yellow") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Black");
        }
     }
     while(phrase1 = "yellow"){

        if (phrase2 = "red") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Brown");
        }
        if (phrase2 = "green") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Blue");
        }
        if (phrase2 = "gray") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Green");
        }
        if (phrase2 = "blue") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the Green");
        }
        if (phrase2 = "black") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Black");
        }
     }
     while(phrase1 = "Blue"){

        if (phrase2 = "red") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Brown");
        }
        if (phrase2 = "green") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Brown");
        }
        if (phrase2 = "gray") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the Dark blue");
        }
        if (phrase2 = "yellow") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the Green");
        }
        if (phrase2 = "black") {
            System.out.print("Combining" + " " + phrase1 + " " + "with" + " " + phrase2 + " " + "will give you the color Black");
        }
    }
}

}

所以我收到一条错误消息说：

    Exception in thread "main" java.lang.Error: Unresolved compilation problems: 
    Duplicate local variable rand2
    Type mismatch: cannot convert from String to Boolean.

而且我不确定如何解决这个问题 - 请提供任何帮助。

4

5 回答 5

5

首先=是赋值，你必须使用==布尔运算符。

其次，要在 Java 中比较字符串，您需要在equals()字符串上调用方法。

if ("red".equals(phrase2)) {
    // logic here
}

第三，您分配 rand2 两次。您必须第二次使用另一个变量，或者您必须删除该int指示。

int rand2 = (int) (Math.random() * colorsLength);

while(rand1==rand2){
    rand2 = (int) (Math.random() * colorsLength);
}
于 2013-07-29T18:12:51.927 回答
1

您遇到的一个问题是：

while(rand1==rand2){
    int rand2 = (int) (Math.random() * colorsLength);
}

你已经声明了rand2，所以不要再这样做了。您应该将其更改为：

while(rand1==rand2){
    rand2 = (int) (Math.random() * colorsLength);
}

另一件事是，您将赋值运算符 ( =) 与相等运算符 ( )混合在一起==。前者为变量赋值，后者检查变量是否相等。

当您尝试匹配变量时，请使用==.

最后，在 Java 中，您不能使用相等运算符来检查字符串 - 这将逐个匹配一个对象并查看它们是否是同一个对象。您必须改用该equals方法，如下所示：

while(phrase1.equals("green"))

而不是这个：

while(phrase1 = "green")

甚至while(phrase1 == "green")（适用于整数/布尔值/其他类型）。

于 2013-07-29T18:17:03.453 回答
0

为了在 Java 中比较字符串，您必须使用 equals() 方法使用"red".equals(phrase2)或"red".equalsIgnoreCase(phrase2)

==Java中的运算符用于检查相等性，=是一个赋值运算符。但是Java中的字符串是对象，String.class所以==进行引用检查而不是值检查。

因此，要比较 Java 中的两个对象，请使用equals()方法。

于 2013-07-29T18:13:45.540 回答
0

这里有一个语法错误：

  int rand1 = (int) (Math.random() * colorsLength);
  int rand2 = (int) (Math.random() * colorsLength);

  while(rand1==rand2){
      //int rand2 = (int) (Math.random() * colorsLength); - wrong
      //rand2 is already defined, you can write only
      rand2 = (int) (Math.random() * colorsLength);
  }

另外，如果你想要 2 个不同的随机数，你可以：

  int rand1 = (int) (Math.random() * colorsLength);
  int rand2 = (int) (Math.random() * (colorsLength-1));
  if(rand2 >= rand1) rand2++;
于 2013-07-29T18:16:39.770 回答
0

好的。你在这里写的东西有很多问题。我会尽力帮助您解决其中的一些问题。

首先，正如 bas 指出的那样，一般来说，如果你想比较两个值是否相等，你使用 ==，而不是 =。例如：

if ( x == y ) {
  //DO STUFF
}

其次，bas 也指出了这一点，在 Java 中你不能使用 == 来比较字符串。你需要做的是：

if ( string1.equals(string2) ) {
  //DO STUFF
}

第三。“尽管”。这会给你带来很多问题。While 意味着继续执行后面的代码，直到其测试为假。所以，当你这样做时：

while ( myString.equals( "bananas" ) ) {
  System.out.println ( "Lots of bananas." );
}

如果字符串是“bananas”，那么你会得到这个：

Lots of bananas.
Lots of bananas.
Lots of bananas.
Lots of bananas.
Lots of bananas.
Lots of bananas.
Lots of bananas.
Lots of bananas.
....

永远。你真正想要使用的是另一个 if。实际上，这里也有一个方便的逻辑。您可以修改语句以使用 else ifs，而不是一堆 if，因为所有这些选项都是互斥的：

if ( string1.equals("yellow")) {
  if ( string2.equals("green")) {
    System.out.println("stuff");
  }
  else if ( string2.equals("blue")) {
    System.out.println("more stuff");
  }
}
else if ( string1.equals("green")) {
  if ( string2.equals("blue")) {
    System.out.println("lalala");
  }
  else if ( string2.equals("yellow")) {
    System.out.println("more stuff");
  }
}

还有一些更好的方法来编写这个程序，这些方法涉及更少的代码重复和最终更简单的逻辑，但为了避免让你超负荷，现在这可能就足够了。

于 2013-07-29T18:26:23.437 回答