Java --从数组中删除重复元素时出错

Question

我知道有些人已经问过关于副本的问题，我已经看过了所有这些答案，但似乎都没有帮助我/我仍然无法编译它。我的代码中有没有什么明显的遗漏？帮助(编程新手！)

我需要编写一个方法，它接受一个参数，一个字符串值的数组，并返回一个没有重复值的新数组，并且不需要对原始数组进行排序。例如

String [] abc = {"A", "C", "C", "B", "A", "C", "B", "B", "A"};
String [] new = removeDuplicates (abc);
for (int i = 0; i < new.length; i++)
{
    System.out.print (new[i] + " ");
}
System.out.println();

输出应该是:A、C、B

下面是我的代码：

    import java.util.*;

    class Duplication
    {
        public static void main (String [] args)
        {
            String [] values = {"A", "C", "C", "B", "A", "C", "B", "B", "A"};
            String [] newList = removeDuplicates (values);
        }
        private static String removeDuplicates (String [] originalArray)
        {
            for (int i = 0; i < newList.length; i++)
            {
                System.out.print (newList[i] + " ");
            }
            System.out.println();

            String noDuplicates = originalArray.length;
            for (int d = 0; d < noDuplicates; d++)
            {
                for (int e = d + 1; e < noDuplicates; e++)
                {
                    if(originalArray[d] == originalArray[e])
                    {
                        originalArray[e] = originalArray[noDuplicates-1];
                        noDuplicates--;
                        e--;
                    }
                }
            }
        }  
    }

六个错误：

    Duplication.java:9: error: incompatible types
    String [] newList = removeDuplicates (values);
                                     ^
    required: String[]
    found:    String
    Duplication.java:14: error: cannot find symbol
    for (int i = 0; i < newList.length; i++)
                        ^
    symbol:   variable newList
    location: class Duplicates
    Duplication.java:16: error: cannot find symbol
        System.out.print (newList[i] + " ");
                          ^
    symbol:   variable newList
    location: class Duplicates
    Duplication.java:21: error: incompatible types
    String noDuplicates = originalArray.length;
                                       ^
    required: String
    found:    int
    Duplication.java:32: error: bad operand types for binary operator '-'
                originalArray[e] = originalArray[noDuplicates-1];
                                                             ^
    first type:  String
    second type: int
    Duplication.java:35: error: bad operand type String for unary operator '--'
                noDuplicates--;
                            ^

Answer 1

这在java中是无效的：

public static void main (String [] args)
String [] values = {"A", "C", "C", "B", "A", "C", "B", "B", "A"};
String [] newList = removeDuplicates (values);

您必须添加{ }来定义静态main方法的作用域：

public static void main (String [] args){
      String[] values = {"A", "C", "C", "B", "A", "C", "B", "B", "A"};
      String[] newList = removeDuplicates (values);
}

Answer 2

1)您的方法removeDuplicates ()返回一个字符串。在主代码块中，您需要一个字符串数组。

2)作用域变量newList在主块内。因此，此变量在removeDuplicates方法中不可见

3) "originalArray.length“返回"int"，不是字符串。

Answer 3

您应该阅读错误消息。

 Duplication.java:9: error: incompatible types
 String [] newList = removeDuplicates (values);

此函数返回非String []的String

 private static String removeDuplicates (String [] originalArray)

您应该将它声明为

 private static String [] removeDuplicates (String [] originalArray)

您应该在函数的作用域内声明newList才能使用它，这会导致

Duplication.java:14: error: cannot find symbol
for (int i = 0; i < newList.length; i++)

长度是整数，应按如下方式处理：

int noDuplicates = originalArray.length;

仔细阅读编译错误，它们解决了所有问题。