返回新对象，覆盖Java中的现有对象

Question

注意：这是一项任务。

嗨，

好吧，我有这样的方法，将创造的2套一个所谓的工会。

我

mport java.io.*; 

class Set { 

     public int numberOfElements; 
     public String[] setElements; 
     public int maxNumberOfElements; 

     // constructor for our Set class 

     public Set(int numberOfE, int setE, int maxNumberOfE) { 
      this.numberOfElements = numberOfE; 
      this.setElements = new String[setE]; 
      this.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] != null && 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++) { 
       if (setElements[i] != null) { 
        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[] newXtemparray = new String[x.getLength()]; 
      String[] newYtemparray = new String[y.getLength()]; 
      int len = newYtemparray.length + newXtemparray.length; 
      Set temp = new Set(0,len,len); 
      newXtemparray = x.getMember(); 
      newYtemparray = x.getMember(); 
      for(int i = 0; i < newYtemparray.length; i++) { 
       temp.add(newYtemparray[i]); 
      } 

      for(int j = 0; j < newXtemparray.length; j++) { 
       temp.add(newXtemparray[j]); 
      } 
      return temp; 
     } 

    Set difference(Set x, Set y) { 
      String[] newXtemparray = new String[x.getLength()]; 
      String[] newYtemparray = new String[y.getLength()]; 
      int len = newYtemparray.length + newXtemparray.length; 
      Set temp = new Set(0,len,len); 
      newXtemparray = x.getMember(); 
      newYtemparray = x.getMember(); 
      for(int i = 0; i < newXtemparray.length; i++) { 
       temp.add(newYtemparray[i]); 
      } 

      for(int j = 0; j < newYtemparray.length; j++) { 
       int retval = temp.findElement(newYtemparray[j]); 
       if(retval != -1) { 
        temp.remove(newYtemparray[j]); 
       } 
      } 
      return temp; 
     } 
} 

// 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(0,10,10); 
    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 sixb 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); 
    setB.add("b"); 
    setB.add("z"); 
    setB.add("x"); 
    setB.add("y"); 
    Set setC = setA.union(setB,setA); 
    System.out.println("Elements of setA"); 
    setA.printSet(); 
    System.out.println("Union of setA and setB"); 
    setC.printSet(); 
    } 
} 

工会法工作，不知怎的，我可以调用另一个方法就可以了感觉，但它不会做的工作，我理应将创建和组A和组B的所有元素的联盟，而且它只返回setB的元素。输出示例如下：

java SetDemo 
Enter string element to be added 
hello 
You entered hello 
Set size is: 10 
Set is empty? false 
Element sixb is member of setA? -1 
Set is full? true 
Element b located on index: 2 
Set size is: 9 
Elements of setA 
Member elements on index: 0 hello 
Member elements on index: 1 world 
Member elements on index: 2 six 
Member elements on index: 3 seven 
Union of setA and setB 
Member elements on index: 0 b 
Member elements on index: 1 z 
Member elements on index: 2 x 
Member elements on index: 3 y 

感谢， 羽扇

Answer 1

在union()，你这里有一个错字：

newYtemparray = x.getMember(); 

应该

newYtemparray = y.getMember();