我编写了一个程序，用一个按钮按下用户输入的单词，并将它们放入ArrayList中。还有另一个文本字段，用户可以在其中输入字母或单词，用户可以通过另一个按钮按下在ArrayList中搜索。我正在使用顺序搜索算法来完成此任务，但它不能像我期望的那样工作;如果找到搜索到的单词，则应返回搜索功能，并在textArea中打印出找到该单词的位置以及找到该单词的位置。这有效，但仅适用于第一次搜索。如果找不到该单词，则该函数应打印出未找到该单词。这是我想要的。
问题是，在我搜索了一个单词后，它显示了ArrayList中可以找到的位置，当我按下按钮后没有任何反应，无论输入的字母/单词是否在数组中。这就像文本存储的字符串没有变化。我不明白为什么......以下是搜索功能的自定义Class，然后是我的Main类：
public class Search {
static private int i;
static String index;
static boolean found = false;
public static String sequencial (ArrayList<String> list, String user) {
for (int i = 0; i < list.size(); i++) {
if (list.get(i).equals(user)) {
index = "The word " + user + " exist on the place " + i + " in the Arraylist";
found = true;
}
}
if (!found) {
index = "The word " + user + " could not be found";
}
return index;
}
我的Main课程：
ArrayList<String> list = new ArrayList<String>();
ArrayList<String> s = new ArrayList<String>();
private void btnAddActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
txtaOutput.setText("");
String word = txtfAdd.getText();
list.add(word);
for (int i = 0; i < list.size(); i++) {
txtaOutput.append("" + list.get(i) + "\n");
}
}
private void btnSearchActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
String user = txtfSearch.getText();
txtaOutput.setText("");
String index = Search.sequencial(list, user);
txtaOutput.setText("" + index);
}
感谢任何帮助！
答案 0 :(得分：5)
问题是您将found变量声明为static。当找到你的第一个单词时，它被设置为true，并且没有任何东西将它设置为假。而不是使它成为一个静态变量，在sequencial（它的拼写为顺序，顺便说一句）函数中将其声明为局部变量，就在for循环之前。
事实上，您声明为静态的所有变量都应该是本地的。声明静态变量从不是一个好主意。
答案 1 :(得分：1)
正如其他用户所说：
List#indexOf(Object)方法。您应该使用它而不是重新发明轮子（除非您需要，在这种情况下，您可能会看一下ArrayList实现）。还有其他收藏品，例如HashSet更适合查找，但我想这是另一个历史。这将是您的代码的略微简化/更正版本：
// Ommit those unneeded static variables
public static String sequencial (ArrayList<String> list, String user) {
int indexFound = list.indexOf(user);
if (user >= 0) {
return "The word " + user + " exist on the place " + indexFound + " in the Arraylist";
} else {
return "The word " + user + " could not be found";
}
}
...
private void btnSearchActionPerformed(java.awt.event.ActionEvent evt) {
String user = txtfSearch.getText();
// txtaOutput.setText("");
String seqMessage = sequencial(list, user);
txtaOutput.setText(seqMessage);
}
答案 2 :(得分：0)
当您想使用常量时，我们使用静态属性。您不应在此处使用静态属性。当您找到的属性第一次更改时，会发生此问题，不会再次更改。从那时起，它将永远是真实的。与index属性类似。以下是您可以解决此问题的代码：
public class Search {
public static SearchResult sequencial (ArrayList<String> list, String user) {
SearchResult result = null;
for (int i = 0; i < list.size(); i++) {
if (list.get(i).equals(user)) {
String index = "The word " + user + " exist on the place " + i + " in the Arraylist";
boolean found = true;
result = new SearchResult(index, found);
break;
}
}
if (result == null) {
String index = "The word " + user + " could not be found";
result = new SearchResult(index);
}
return result;
}
//sample inner class
static class SearchResult {
private String index;
private boolean found;
public SearchResult(String index) {
this.index = index;
}
public SearchResult(String index, boolean found) {
this.index = index;
this.found = found;
}
public String getIndex() {
return index;
}
public void setIndex(String index) {
this.index = index;
}
public boolean isFound() {
return found;
}
public void setFound(boolean found) {
this.found = found;
}
}
}
答案 3 :(得分：0)
public class SequencialSearcher {
public static int SequencialSearchInt(int[] inputArray, int key)
{
for(int i=0; i < inputArray.length ; i++)
{
if(inputArray[i] == key)
{
return i;
}
}
return -1;
}
public static int SequencialSearchString(String[] array, String key)
{
for(int i=0; i < array.length ; i++)
{
if(array[i] == key)
{
return i;
}
}
return -1;
}
public static int SequencialSearchFloat(double[] array, double key)
{
for(int i=0; i < array.length ; i++)
{
if(array[i] == key)
{
return i;
}
}
return -1;
}
public static void main (String args[])
{
//select the type of the elements of search
//1 if integers
//2 if float
//3 if string
int x = 3;
int[] array1 = {9, 0, 10, 8, 5, 4, 6, 2, 3};
double[] array2 = {9.0, 0.0, 10.0, 8.0, 5.0, 4.0, 6.0, 2.0, 3.0};
String[] array3 = {"aa","hey", "hello"};
if(x == 1){
//enter the integer you want to search for here below
int requiredValue = 5;
int result = SequencialSearchInt(array1, requiredValue);
if (result != -1)
{
System.out.println("Required Value: "+requiredValue+" found at index: "+result);
}
else
{
System.out.println("Value:"+requiredValue+" not found");
}
}
else if(x == 2)
{
//enter the double you want to search for here below
double requiredValue1 = 5.0;
int result = SequencialSearchFloat(array2, requiredValue1);
if (result != -1)
{
System.out.println("Required Value: "+requiredValue1+" found at index: "+result);
}
else
{
System.out.println("Value:"+requiredValue1+" not found");
}
}
else if(x == 3){
//enter the string you want to search for here below
String requiredValue2 = "hey";
int result = SequencialSearchString(array3, requiredValue2);
if (result != -1)
{
System.out.println("Required Value: "+requiredValue2+" found at index: "+result);
}
else
{
System.out.println("Value:"+requiredValue2+" not found");
}
}
else{
System.out.println("Error. Please select 1,2 and 3 only");
}
}
}