[英]Java Insertion Sorting with ArrayLists of Strings
I have an assignment on sorting which requires me to sort a list of random words by putting letters that start with the same letter in a group/zones and sorting that group alphabetically.我有一个关于排序的任务,要求我通过将以相同字母开头的字母放在组/区域中并按字母顺序对该组进行排序来对随机单词列表进行排序。 My code sorts the words but my problem is that some of the words have changed.
我的代码对单词进行了排序,但我的问题是某些单词已经改变。 For example instead of having an output as
例如,而不是将 output 作为
I would have an output of:我会有一个 output :
As you can see, some of the words have been changed and in some cases, words with a capital letter are turned into lower cases like "cat" and I can't seem to find where my mistake is.正如你所看到的,一些单词已经改变,在某些情况下,大写字母的单词变成了小写字母,比如“cat”,我似乎找不到我的错误在哪里。
This is my sorting code;这是我的排序代码; my driver class just takes in the list of random words:
我的驱动程序 class 只接受随机单词列表:
import java.util.ArrayList;
import java.util.Collections;
public class ZoneSort
{
ArrayList[] arrayOfZones;
ArrayList<String> words;
public ZoneSort(ArrayList<String> words)
{
arrayOfZones = new ArrayList [ 26 ];
for(int index = 0; index < 26;index++)
arrayOfZones [ index ] = new ArrayList();
this.words = words;
putWordsIntoZones();
}
private void putWordsIntoZones()
{
for(String word: words)
{
int index = Character.toLowerCase(word.charAt(0)) - 97;
ArrayList<String> zoneAtIndex = arrayOfZones[index];
zoneAtIndex.add(word);
}
}
public void sortTheArrayOfZones()
{
for(ArrayList<String> zone : arrayOfZones )
{
sortZone(zone);
}
}
private void sortZone(ArrayList<String> zone)
{
for(int i = 1; i < zone.size(); i++)
{
String key = zone.get(i);
int j = i-1;
while(j>=0 && key.compareTo(zone.get(j)) > 0)
{
String x = zone.get(j+1);
zone.set(j, x);
j--;
}
String x = zone.get(j+1);
x = key;
}
}
public void printArrayOfZones()
{
System.out.println("The sorted words are");
for(ArrayList<String> zone:arrayOfZones)
{
for(String word: zone)
{
System.out.println(word);
}
}
}
Reading your code and viewing your results, it seems that your code overwrites the values instead of swapping them.阅读您的代码并查看您的结果,您的代码似乎覆盖了这些值而不是交换它们。 To fix this you need to take a look at the function sort.
要解决此问题,您需要查看 function 排序。 I have modified your code so that instead of overwriting, you swap the two elements:
我已经修改了您的代码,以便您交换两个元素,而不是覆盖:
private void sortZone(ArrayList<String> zone){
for(int i = 1; i < zone.size(); i++){
String key = zone.get(i);
int j = i-1;
while(j>=0 && key.compareTo(zone.get(j)) > 0){
String x = zone.get(j+1);
zone.set(j+1,zone.get(j)); // line added
zone.set(j, x);
j--;
}
String x = zone.get(j+1);
x = key;
}
}
I hope this fixed your problem.我希望这解决了你的问题。
If I compare your sortZone implementation with a reference insertion sort implementation such as https://www.baeldung.com/java-insertion-sort I see the following differences - see inline comments如果我将您的 sortZone 实现与参考插入排序实现(例如https://www.baeldung.com/java-insertion-sort )进行比较,我会看到以下差异 - 请参阅内联注释
for(int i = 1; i < zone.size(); i++)
{
String key = zone.get(i);
int j = i-1;
// The sort order is reversed.
// You've used "key > zone[j]" when it should be "key < zone[j]"
while(j>=0 && key.compareTo(zone.get(j)) < 0)
{
// This is copying items backwards, towards the beginning of the array.
// String x = zone.get(j+1);
// zone.set(j, x);
// It should be copying items forwards, towards the end, to make room for "key"
// Like this:
String x = zone.get(j);
zone.set(j+1, x);
j--;
}
// You should be setting zone[j+1] = "key" - this does not do it:
// String x = zone.get(j+1);
// x = key;
// This is how you set a value in a list:
zone.set(j+1, key);
}
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