實現使用基本java數組的集合

Question

注意：這是一項任務。

繼續使用Java基本數組實現我的Set實現，現在我正在努力使用3到最後一個函數，即union。

import java.io.*; 

class Set { 

     private int numberOfElements = 0; 
     private String[] setElements = new String[5]; 
     private int maxNumberOfElements = 5; 

     // constructor for our Set class 

     public Set(int numberOfE, int setE, int maxNumberOfE) { 
      int numberOfElements = numberOfE; 
      String[] setElements = new String[setE]; 
      int maxNumberOfElements = maxNumberOfE; 
     } 

     // Helper method to shorten/remove element of array since we're using basic array instead of ArrayList or HashSet from collection interface :(

     static String[] removeAt(int k, String[] arr) { 
      final int L = arr.length; 
      String[] ret = new String[L - 1]; 
      System.arraycopy(arr, 0, ret, 0, k); 
      System.arraycopy(arr, k + 1, ret, k, L - k - 1); 
      return ret; 
     } 

     int findElement(String element) { 
      int retval = 0; 

      for (int i = 0; i < setElements.length; i++) { 

       if (setElements[i] != null && setElements[i].equals(element)) { 
        return retval = i; 

       } 
      retval = -1; 
      } 

      return retval; 
     } 

     void add(String newValue) { 
      int elem = findElement(newValue); 
      if(numberOfElements < maxNumberOfElements && elem == -1) { 
       setElements[numberOfElements] = newValue; 
       numberOfElements++; 
      } 
     } 

     int getLength() { 
      if (setElements != null) { 
       return setElements.length; 
      } 
      else { 
       return 0; 
      } 
     } 

     String[] emptySet() { 
      setElements = new String[0]; 
      return setElements; 
     } 


     Boolean isFull() { 
      Boolean True = new Boolean(true); 
      Boolean False = new Boolean(false); 
      if (setElements.length == maxNumberOfElements){ 
       return True; 
      } else { return False; } 
     } 

     Boolean isEmpty() { 
      Boolean True = new Boolean(true); 
      Boolean False = new Boolean(false); 

      if (setElements.length == 0) { 
       return True; 
      } else { return False; } 
     } 

     void remove(String newValue) { 

      for (int i = 0; i < setElements.length; i++) { 
       if (setElements[i].equals(newValue)) { 
        setElements = removeAt(i,setElements); 

       } 
      } 

     } 

     int isAMember(String element) { 
      int retval = -1; 

      for (int i = 0; i < setElements.length; i++) { 
       if (setElements[i] != null && setElements[i].equals(element)) { 
        return retval = i; 
       } 
      } 
      return retval; 
     } 

     void printSet() { 
      for (int i = 0; i < setElements.length; i++) { 
       System.out.println("Member elements on index: "+ i +" " + setElements[i]); 
      } 
     } 

     String[] getMember() { 
      String[] tempArray = new String[setElements.length]; 
      for (int i = 0; i < setElements.length; i++) { 
       if(setElements[i] != null) { 
        tempArray[i] = setElements[i]; 
       } 
      } 
      return tempArray; 
     } 

     Set union(Set x, Set y) { 
      String[] newtemparray = new String[x.getLength]; 
      newtemparray = x.getMember; 
      return x; 
     } 

} 

// This is the SetDemo class that will make use of our Set class 

class SetDemo { 
    public static void main(String[] args) { 
      //get input from keyboard 
      BufferedReader keyboard; 
      InputStreamReader reader; 
      String temp = ""; 

      reader = new InputStreamReader(System.in); 
      keyboard = new BufferedReader(reader); 


     try 
      { 
       System.out.println("Enter string element to be added"); 
       temp = keyboard.readLine(); 
       System.out.println("You entered " + temp); 
      } 
    catch (IOException IOerr) 
      { 
       System.out.println("There was an error during input"); 
      } 

    /* 
     ************************************************************************** 
     * Test cases for our new created Set class. 
     * 
     ************************************************************************** 
    */ 
    Set setA = new Set(1,10,10); 
    setA.add(temp); 
    setA.add("b"); 
    setA.add("b"); 
    setA.add("hello"); 
    setA.add("world"); 
    setA.add("six"); 
    setA.add("seven"); 
    setA.add("b"); 
    int size = setA.getLength(); 
    System.out.println("Set size is: " + size); 
    Boolean isempty = setA.isEmpty(); 
    System.out.println("Set is empty? " + isempty); 
    int ismember = setA.isAMember("sixb"); 
    System.out.println("Element six is member of setA? " + ismember); 
    Boolean output = setA.isFull(); 
    System.out.println("Set is full? " + output); 
    setA.printSet(); 
    int index = setA.findElement("world"); 
    System.out.println("Element b located on index: " + index); 
    setA.remove("b"); 
    setA.emptySet(); 
    int resize = setA.getLength(); 
    System.out.println("Set size is: " + resize); 
    setA.printSet(); 
    Set setB = new Set(0,10,10); 
    Set SetA = setA.union(setB,setA); 
    } 
} 

好吧，有問題的方法將實施工會。因此，這：

Set union(Set x, Set y) { 
      String[] newtemparray = new String[x.getLength]; 
      newtemparray = x.getMember; 
      return x; 
     } 

我得到這個錯誤：

symbol : variable getLength 
location: class Set 
      String[] newtemparray = new String[x.getLength]; 
              ^
d:\javaprojects\Set.java:122: cannot find symbol 
symbol : variable getMember 
location: class Set 
      newtemparray = x.getMember; 
         ^
2 errors 

我對聯盟的做法是：

• 創建對象x長度的字符串大小的臨時數組。
• 通過循環對象和調用getMember將對象x成員存儲到臨時數組
• 循環對象y成員並檢查對臨時數組是否存在元素。
• 丟棄是否存在/添加，如果它不存在
• 返回obj x與聯合數組。

Answer 1

您遇到的問題是x.getLength是一個函數，而不是成員。你需要調用x.getLength（）來代替。

Answer 2

它分別是x.getLength()和x.getMember()。

getLength()和getMember()是Set，因此你需要()因爲你調用一個方法