java - 链表对象的 substring() 方法-6ren

java - 链表对象的 substring() 方法

转载作者：行者123 更新时间：2023-12-02 04:55:01

我在为我正在构建的名为 LString 的类编写 substring() 方法时遇到一些问题。此类创建一个名为 LString 的链表对象，用于构建字符串。它模仿 Java 中的 String 和 StringBuilder 对象。

substring(int start, int end) 根据 提供的索引，从给定的 this LString 创建一个新的 LString >开始到结束。它返回类型LString。

以下是错误消息，未进行任何编辑以使 end 包含在内:

Running substring tests (63 tests)
Starting tests: ......E........................................................
Time: 0.031

There was 1 failure:
1) test43cSubStringOneChar(LStringTest$LStringSubStringTestSpecial)
java.lang.AssertionError: Substring of One Character LString is not equals LString expected: LString<a> but was: LString<a>
        at org.junit.Assert.fail(Assert.java:88)
        at org.junit.Assert.failNotEquals(Assert.java:743)
        at org.junit.Assert.assertEquals(Assert.java:118)
        at LStringTest$LStringSubStringTestSpecial.test43cSubStringOneChar(LStringTest.java:401)
        ... 10 more

Test Failed! (1 of 63 tests failed.)

Test failures: abandoning other phases.

这会产生一个更简单的错误消息，只有 1 次失败。

以下是与该错误消息对应的代码:

import java.io.*;
import java.util.*;

public class LString    {

     node   front;
     int size;

     //Creating a node class
     private    class   node {
          char data;
          node next;

          public    node (){
          }

          public    node    (char   newData){
                this.data = newData;
          }

          public    node    (char   newData,    node newNext){
                this.data = newData;
                this.next = newNext;
          }


     }
     //Constructors
     public LString(){
          this.size =   0;
          this.front =  null;
     }
     public LString(String original)    {
          this.size = original.length();
          if (original.length() > 0){

              this.front =  new node(original.charAt(0));
              node curr = this.front;

              for   (int i =1; i <  original.length(); i++) {
                    curr.next = new node(original.charAt(i));
                    curr = curr.next;
              }
          }



     }

    //  Length method,  returns the length of LString
     public int length()    {
        return this.size;
    }

    //  compareTo method,   compares    this LString to anotherLString, returns 0   if  equal,
    //  -1  if  lexicogrpahically   less,   and 1   if  lexicographically   greater
    public int compareTo(LString anotherLString)    {
        int len1    = length();
        int len2    = anotherLString.length();
        int lim = Math.min(len1, len2);

        node cn1    = front;
        node cn2    = anotherLString.front;

        int k   = 0;
        while   (k  < lim) {
            char c1 = cn1.data;
            char c2 = cn2.data;
            if  (c1 != c2) {
                return c1-c2;
            }
            k++;
            cn1 =   cn1.next;
            cn2 =   cn2.next;
        }
        return len1 - len2;

    }

    //  a boolean equals method that returns true   if  LString and other   are the same, false if not
    public boolean  equals(Object other)    {
        if  (this   ==  other) {
            return true;
        }
        if  (other instanceof   LString)    {
            LString otherLString    = (LString)other;
            int n   = length();
            if  (n  ==  otherLString.length()) {
                node n1 = front;
                node n2 = otherLString.front;
                while   (n1 != null) {
                    if  (n1.data    !=  n2.data)    {
                        return false;
                    }
                    n1  = n1.next;
                    n2  = n2.next;
                }
                return true;
            }
        }

        return false;
    }


    //  charAt returns  the character of LString at the argument index
    public char charAt(int index)   {

        if  ((index < 0) || (index >= this.length()))   {
            throw   new IndexOutOfBoundsException();
        }
        node curNode =  front;
        for (int    i = 0; i    < this.length(); i++, curNode   = curNode.next) {
            if  (i  ==  index) {
                return curNode.data;
            }
        }
        throw   new IllegalStateException();
    }

    //
    public void setCharAt(int index,    char ch)    {
      if (index < 0 || index >= this.length()) {
         throw new IndexOutOfBoundsException();
      }
      else {
         node currNode = front;
         for (int i = 0; i <this.length(); i++, currNode = currNode.next) {
            if (i == index) {
            currNode.data = ch;
            }
         }
      }
   }

    public LString  substring(int start,    int end)    {
      if (start < 0 || end > this.length() || start > end) {
         throw new IndexOutOfBoundsException();
      }
      LString substring = new LString();
      if (start == end) {
         return substring;
      }
      node node = this.front;
      for (int i = 0; i < start; i++) {
         node = node.next;
      }
      node copy = new node(node.data);
      substring.front = copy;
      for (int i = start+1; i < end; i++) {
         node = node.next;
         copy = copy.next = new node(node.data);
      }
      return substring;      
    }
    public LString  replace(int start, int end, LString lStr)   {
        return null;
    }

    public String toString(){
        StringBuilder result    = new   StringBuilder();

        node curr = front;
        while   (curr   !=  null){

            result.append(curr.data);
            curr = curr.next;
        }
        return result.toString();
    }
}

一些注意事项:我确实编写了一个 toString() 方法，在这段代码中还有一个 replace() 方法，我将在这之后编写。

以下是使 end 包含在内的错误和代码:

错误:

Running substring tests (63 tests)
Starting tests: E....EEE....E.EEEEEE.....E.EEEEEEE....E.EEEEEEE....E.EEEEEEE...
Time: 0.028

There were 35 failures:
1) test41aSubStringEmpty(LStringTest$LStringSubStringTestSpecial)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTestSpecial.test41aSubStringEmpty(LStringTest.java:368)
        ... 10 more
2) test43bSubStringOneChar(LStringTest$LStringSubStringTestSpecial)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTestSpecial.test43bSubStringOneChar(LStringTest.java:395)
        ... 10 more
3) test43cSubStringOneChar(LStringTest$LStringSubStringTestSpecial)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTestSpecial.test43cSubStringOneChar(LStringTest.java:401)
        ... 10 more
4) test43dSubStringOneCharIsNew(LStringTest$LStringSubStringTestSpecial)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTestSpecial.test43dSubStringOneCharIsNew(LStringTest.java:407)
        ... 10 more
5) test51bEmptySubstringAtEnd[0](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51bEmptySubstringAtEnd(LStringTest.java:468)
        ... 10 more
6) test51dSubstringAtStart[0](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(0, mid) is not correct expected:<a[]> but was:<a[b]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51dSubstringAtStart(LStringTest.java:478)
        ... 10 more
7) test51eSubstringAtEnd[0](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51eSubstringAtEnd(LStringTest.java:483)
        ... 10 more
8) test51fSubstringInMiddle[0](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(left, right) is not correct expected:<[]> but was:<[b]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51fSubstringInMiddle(LStringTest.java:488)
        ... 10 more
9) test51gSubstringAll[0](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51gSubstringAll(LStringTest.java:493)
        ... 10 more
10) test51hSubstringAtStartIsNew[0](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(0, mid) is not new LString expected:<a[]> but was:<a[b]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51hSubstringAtStartIsNew(LStringTest.java:500)
        ... 10 more
11) test51jSubstringAtEndIsNew[0](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51jSubstringAtEndIsNew(LStringTest.java:505)
        ... 10 more
12) test51bEmptySubstringAtEnd[1](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51bEmptySubstringAtEnd(LStringTest.java:468)
        ... 10 more
13) test51dSubstringAtStart[1](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(0, mid) is not correct expected:<a[]> but was:<a[b]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51dSubstringAtStart(LStringTest.java:478)
        ... 10 more
14) test51eSubstringAtEnd[1](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51eSubstringAtEnd(LStringTest.java:483)
        ... 10 more
15) test51fSubstringInMiddle[1](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(left, right) is not correct expected:<b[]> but was:<b[c]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51fSubstringInMiddle(LStringTest.java:488)
        ... 10 more
16) test51gSubstringAll[1](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51gSubstringAll(LStringTest.java:493)
        ... 10 more
17) test51hSubstringAtStartIsNew[1](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(0, mid) is not new LString expected:<a[]> but was:<a[b]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51hSubstringAtStartIsNew(LStringTest.java:500)
        ... 10 more
18) test51jSubstringAtEndIsNew[1](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51jSubstringAtEndIsNew(LStringTest.java:505)
        ... 10 more
19) test51kSubstringInMiddleIsNew[1](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(left, right) is not new LString expected:<b[]> but was:<b[c]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51kSubstringInMiddleIsNew(LStringTest.java:515)
        ... 10 more
20) test51bEmptySubstringAtEnd[2](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51bEmptySubstringAtEnd(LStringTest.java:468)
        ... 10 more
21) test51dSubstringAtStart[2](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(0, mid) is not correct expected:<A long []> but was:<A long [s]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51dSubstringAtStart(LStringTest.java:478)
        ... 10 more
22) test51eSubstringAtEnd[2](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51eSubstringAtEnd(LStringTest.java:483)
        ... 10 more
23) test51fSubstringInMiddle[2](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(left, right) is not correct expected:<ng str[]> but was:<ng str[i]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51fSubstringInMiddle(LStringTest.java:488)
        ... 10 more
24) test51gSubstringAll[2](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51gSubstringAll(LStringTest.java:493)
        ... 10 more
25) test51hSubstringAtStartIsNew[2](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(0, mid) is not new LString expected:<A long []> but was:<A long [s]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51hSubstringAtStartIsNew(LStringTest.java:500)
        ... 10 more
26) test51jSubstringAtEndIsNew[2](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51jSubstringAtEndIsNew(LStringTest.java:505)
        ... 10 more
27) test51kSubstringInMiddleIsNew[2](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(left, right) is not new LString expected:<ng str[]> but was:<ng str[i]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51kSubstringInMiddleIsNew(LStringTest.java:515)
        ... 10 more
28) test51bEmptySubstringAtEnd[3](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51bEmptySubstringAtEnd(LStringTest.java:468)
        ... 10 more
29) test51dSubstringAtStart[3](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(0, mid) is not correct expected:<This is an even[]> but was:<This is an even[ ]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51dSubstringAtStart(LStringTest.java:478)
        ... 10 more
30) test51eSubstringAtEnd[3](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51eSubstringAtEnd(LStringTest.java:483)
        ... 10 more
31) test51fSubstringInMiddle[3](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(left, right) is not correct expected:<an even longer[]> but was:<an even longer[ ]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51fSubstringInMiddle(LStringTest.java:488)
        ... 10 more
32) test51gSubstringAll[3](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51gSubstringAll(LStringTest.java:493)
        ... 10 more
33) test51hSubstringAtStartIsNew[3](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(0, mid) is not new LString expected:<This is an even[]> but was:<This is an even[ ]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51hSubstringAtStartIsNew(LStringTest.java:500)
        ... 10 more
34) test51jSubstringAtEndIsNew[3](LStringTest$LStringSubStringTest)
java.lang.IndexOutOfBoundsException
        at LString.substring(LString.java:142)
        at LStringTest$LStringSubStringTest.test51jSubstringAtEndIsNew(LStringTest.java:505)
        ... 10 more
35) test51kSubstringInMiddleIsNew[3](LStringTest$LStringSubStringTest)
org.junit.ComparisonFailure: substring(left, right) is not new LString expected:<an even longer[]> but was:<an even longer[ ]>
        at org.junit.Assert.assertEquals(Assert.java:115)
        at LStringTest$LStringSubStringTest.test51kSubstringInMiddleIsNew(LStringTest.java:515)
        ... 10 more

Test Failed! (35 of 63 tests failed.)

Test failures: abandoning other phases.

以下是代码中的相关差异，仅substring()不同:

public LString  substring(int start,    int end)    {
  if (start < 0 || end >= this.length() || start > end) {
     throw new IndexOutOfBoundsException();
  }
  LString substring = new LString();
  /*if (start == end) {
     return substring;
  }*/
  node node = this.front;
  for (int i = 0; i < start; i++) {
     node = node.next;
  }
  node copy = new node(node.data);
  substring.front = copy;
  for (int i = start; i < end; i++) {
     node = node.next;
     copy = copy.next = new node(node.data);
  }
  return substring;      
}

LStringTest 中有关错误的部分:

   @Test public void test43aSubStringOneChar() {
         LString testLString = new LString("a");
         assertEquals("Substring of One Character LString is not Empty",
               nullLString, testLString.substring(0, 0));
      }

      @Test public void test43bSubStringOneChar() {
         LString testLString = new LString("a");
         assertEquals("Substring of One Character LString is not Empty",
               nullLString, testLString.substring(1, 1));
      }

      @Test public void test43cSubStringOneChar() {
         LString testLString = new LString("a");
         assertEquals("Substring of One Character LString is not equals LString",
               testLString, testLString.substring(0, 1));
      }

最佳答案

其他答案中的代码无法编译，即使编译了，也无法正常运行。

假设您使用标准(对于 Java)从零开始的索引，并且 end 索引是独占的，此代码将进行编译和测试。

public LString substring(int start, int end) {
    if (start < 0 || end > length() || start > end) {
        throw new IndexOutOfBoundsException();
    }
    LString result = new LString();
    if (start == end) {
        return result;
    }
    node node = this.front;
    for (int i = 0; i < start; i++) {
        node = node.next;
    }
    node copy = new node(node.data);
    result.front = copy;
    for (int i = start + 1; i < end; i++) {
        node = node.next;
        copy = copy.next = new node(node.data);
    }
    result.size = end - start;
    return result;
}

如果您希望 end 具有包容性，尽管这违反了 Java 约定，您需要更改三件事:

方法开头的保护子句必须是 end >= length() 而不是 end > length()，
第二个保护子句 if (start == end) { return substring; } 需要完全删除，并且
最后一个 for 循环将初始化 int i = start，而不是 int i = start + 1。

顺便说一句，如果类中有 toString() 方法，则可以更轻松地查看 LString 实例发生的情况。

@Override
public String toString() {
    if (this.front == null) return "";
    StringBuilder sb = new StringBuilder(length());
    node node = this.front;
    do sb.append(node.data);
    while ((node = node.next) != null);
    return sb.toString();
}

关于java - 链表对象的 substring() 方法，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/28865738/

文章推荐： Java正则表达式替换文本中的字符串

文章推荐： Matlab求解: Solution not satisfying the equation

文章推荐： r - 阻止 R 覆盖图形文件

文章推荐： java - Java 循环中的用户输入和求和问题

java - 对象 a = 对象 b；对象 a 会发生什么？
我的一位教授给了我们一些考试练习题，其中一个问题类似于下面(伪代码): a.setColor(blue); b.setColor(red); a = b; b.setColor(purple); b
JavaScript 测试(对象 && 对象 !== "null"&& 对象 !== "undefined")
我似乎经常使用这个测试 if( object && object !== "null" && object !== "undefined" ){ doSomething(); } 在对象上，我
C#对象/对象
C# Object/object 是值类型还是引用类型？我检查过它们可以保留引用，但是这个引用不能用于更改对象。 using System; class MyClass { public s
javascript - 通过ajax发送json - 对象 - 对象
我在通过 AJAX 发送 json 时遇到问题。 var data = [{"name": "Will", "surname": "Smith", "age": "40"},{"name": "Wil
javascript - 如何获取值[对象][对象]
当我尝试访问我的 View 中的对象 {{result}} 时(我从 Express js 服务器发送该对象)，它只显示 [object][object]有谁知道如何获取 JSON 格式的值吗？这是
java - 对象...对象[] 和格式
我有不同类型的数据(可能是字符串、整数......)。这是一个简单的例子: public static void main(String[] args) { before("one"); }
javascript - 如何修复[对象，对象]
嗨，我是 json 和 javascript 的新手。我在这个网站找到了使用json数据作为表格的方法。我很好奇为什么当我尝试使用 json 数据作为表时，我得到 [Object,Object]
JavaScript [对象][对象] 调试
已关闭。此问题需要 debugging details 。目前不接受答案。编辑问题以包含 desired behavior, a specific problem or error, and the
java - 对象==空或空==对象？
我听别人说 null == object 比 object == null check 例如: void m1(Object obj ) { if(null == obj) // Is thi
VBS教程：对象-Match 对象
Match 对象提供了对正则表达式匹配的只读属性的访问。说明 Match 对象只能通过 RegExp 对象的 Execute 方法来创建，该方法实际上返回了 Match 对象的集合。所有的
VBS教程：对象-Class 对象
Class 对象使用 Class 语句创建的对象。提供了对类的各种事件的访问。说明不允许显式地将一个变量声明为 Class 类型。在 VBScript 的上下文中，“类对象”一词指的是用
VBS教程：对象-Folder 对象
Folder 对象提供对文件夹所有属性的访问。说明以下代码举例说明如何获得 Folder 对象并查看它的属性： Function ShowDateCreated(f
VBS教程：对象-File 对象
File 对象提供对文件的所有属性的访问。说明以下代码举例说明如何获得一个 File 对象并查看它的属性： Function ShowDateCreated(fil
VBS教程：对象-Drive 对象
Drive 对象提供对磁盘驱动器或网络共享的属性的访问。说明以下代码举例说明如何使用 Drive 对象访问驱动器的属性： Function ShowFreeSpac
VBS教程：对象-FileSystemObject 对象
FileSystemObject 对象提供对计算机文件系统的访问。说明以下代码举例说明如何使用 FileSystemObject 对象返回一个 TextStream 对象，此对象可以被读
对象
我是 javascript OOP 的新手，我认为这是一个相对基本的问题，但我无法通过搜索网络找到任何帮助。我是否遗漏了什么，或者我只是以错误的方式解决了这个问题？这是我的示例代码: functio
对象
我可以很容易地创造出很多不同的对象。例如像这样: var myObject = { myFunction: function () { return ""; } };
对象
function Person(fname, lname) { this.fname = fname, this.lname = lname, this.getName = function()
javascript - JSON 返回(对象，对象)
任何人都可以向我解释为什么下面的代码给出 (object, Object) 吗？ (console.log(dope) 给出了它应该的内容，但在 JSON.stringify 和 JSON.parse
javascript - 返回 [对象，对象] 的工具提示
我正在尝试完成散点图 exercise来自免费代码营。然而，我现在只自己学习了 d3 几个小时，在遵循 lynda.com 的教程后，我一直在尝试确定如何在工具提示中显示特定数据。 This code

行者123

个人简介

我是一名优秀的程序员,十分优秀！

作者热门文章

滴滴打车优惠券免费领取

全站热门文章

首页

博学

6Ren·AI

商城

java - 链表对象的 substring() 方法