Question

我从特定表的数据库中获取值并将值添加到Array列表中，添加了值，但在添加最后一个值时，抛出了IndexOutOfBound异常。已附加样本输出以供参考和代码使用。

  **Code:**  ----------
    try {           
        statement = conn.createStatement();
        String exten = ".dbo.";
        String countquery = "select COUNT(" + "" + field + "" + ") from " + "[" + database + "]" + "" + exten + ""+ "[" + table + "]";
                String query = "select " + "" + field + "" + " from " + "[" + database + "]" + "" + exten + "" + "[" + table+ "]";

        ResultSet countrs = statement.executeQuery(countquery);
        while (countrs.next()) {
        System.out.println(countrs.getString(1));
        count = Integer.parseInt(countrs.getString(1));
                }
        ArrayList<String> records = new ArrayList<String>(size);
        System.out.println("HIHIHI" + query);
        ResultSet rs = statement.executeQuery(query);
        rs.next();
        for (int j = 0; j < count; j++) {
        System.out.println(j + rs.getString(field) + records.size());
        records.add(rs.getString(field));
        System.out.println(records.get(j));
        rs.next();
                }
                return records;

            } catch (ArrayIndexOutOfBoundsException exception) {
                exception.printStackTrace();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

**Exception:**

333Luke                          333
Luke                          
334JOHN                          334
JOHN                          
335lotto                         335
lotto                         
336Jasonhhhhhhhhhhhhhhhhhhhhhhhhh336
Jasonhhhhhhhhhhhhhhhhhhhhhhhhh
337Pamela                        337
Pamela                        
338John                          338
[main] INFO net.serenitybdd.core.Serenity - STEP ERROR: java.lang.IndexOutOfBoundsException: Index: 338, Size: 338
[main] INFO net.serenitybdd.core.Serenity - STEP ERROR: java.lang.IndexOutOfBoundsException: Index: 338, Size: 338
[main] INFO net.serenitybdd.core.Serenity - FINISHING STEP
[main] ERROR net.serenitybdd.core.Serenity - 
           __  _____ _____ ____ _____   _____ _    ___ _     _____ ____  
  _       / / |_   _| ____/ ___|_   _| |  ___/ \  |_ _| |   | ____|  _ \ 
 (_)_____| |    | | |  _| \___ \ | |   | |_ / _ \  | || |   |  _| | | | |
  _|_____| |    | | | |___ ___) || |   |  _/ ___ \ | || |___| |___| |_| |
 (_)     | |    |_| |_____|____/ |_|   |_|/_/   \_\___|_____|_____|____/ 
          \_\                                                            

TEST FAILED WITH ERROR: DB check
---------------------------------------------------------------------
[main] ERROR net.serenitybdd.core.Serenity - TEST FAILED AT STEP DB retrievelist: FIRSTNAME, Guru, EMPLOYEE
[main] ERROR net.serenitybdd.core.Serenity - Index: 338, Size: 338

[31mFailed scenarios:[0m
[31mdebug.feature:46 [0m# Scenario Outline: DBCheck

4 Scenarios ([31m1 failed[0m, [32m3 passed[0m)
26 Steps ([31m1 failed[0m, [32m25 passed[0m)
1m49.097s

java.lang.IndexOutOfBoundsException: Index: 338, Size: 338
    at java.util.ArrayList.rangeCheck(ArrayList.java:653)
    at java.util.ArrayList.get(ArrayList.java:429)
    at net.thucydides.showcase.cucumber.webdriverclasses.SQLSupportClass.retrievelist(SQLSupportClass.java:41)
    at net.thucydides.showcase.cucumber.steps.serenity.CommonSteps.DBRetrievelist(CommonSteps.java:84)
    at net.thucydides.showcase.cucumber.steps.serenity.CommonSteps$$EnhancerByCGLIB$$402c7b7f.CGLIB$DBRetrievelist$23(<generated>)
    at net.thucydides.showcase.cucumber.steps.serenity.CommonSteps$$EnhancerByCGLIB$$402c7b7f$$FastClassByCGLIB$$c7f4d865.invoke(<generated>)
    at net.sf.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)
    at net.thucydides.core.steps.StepInterceptor.invokeMethod(StepInterceptor.java:372)
    at net.thucydides.core.steps.StepInterceptor.executeTestStepMethod(StepInterceptor.java:357)
    at net.thucydides.core.steps.StepInterceptor.runTestStep(StepInterceptor.java:332)
    at net.thucydides.core.steps.StepInterceptor.testStepResult(StepInterceptor.java:134)
    at net.thucydides.core.steps.StepInterceptor.intercept(StepInterceptor.java:61)
    at

Answer 1

你有一个太多的rs.next（）语句。

替换这两个rs.next()来电：

rs.next();
for (int j = 0; j < count; j++) {
    System.out.println(j + rs.getString(field) + records.size());
    records.add(rs.getString(field));
    System.out.println(records.get(j));
    rs.next();
}

用这个进行最小的改动：

for (int j = 0; j < count; j++) {
    rs.next();
    System.out.println(j + rs.getString(field) + records.size());
    records.add(rs.getString(field));
    System.out.println(records.get(j));
}

但更好的解决方案是检查next()调用的结果，并在while循环中使用它。当时也不需要计算。

while (rs.next()) {
    records.add(rs.getString(field));
}

跳过整个countQuery的事情，忽略ArrayList的初始大小（或者如果你知道它总是至少几百，将它设置为例如500）。无论如何，它会增长。从两个查询更改为一个查询可能比任何ArrayList调整大小操作要好得多，所以不妨忽略它。

Answer 2

您可以使用一个查询最小化代码。试试吧：

public static void main(String[] args) {
        try {
            statement = conn.createStatement();
            String exten = ".dbo.";
            String query = "select " + "" + field + "" + " from " + "[" + database + "]" + "" + exten + "" + "[" + table + "]";

            ResultSet rs = statement.executeQuery(query);
            //COUNT THE ROWS USING RESULTSET
            count =getCountRows(rs);
            ArrayList<String> records = new ArrayList<>();
            while (rs.next()) {
                records.add(rs.getString(field));

                System.out.println(records.get(records.size()-1));
            }




        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    public static int getCountRows(ResultSet resultSet) {
        int size = 0;
        try {
            resultSet.last();
            size = resultSet.getRow();
            resultSet.beforeFirst();
        } catch (Exception ex) {
            return -1;
        }
        return size;
    }

Answer 3

只保留一个查询语句和一个rs.next（），如下所示。

io.connect('https://test16793.herokuapp.com/');

向Array List添加值时抛出java.lang.IndexOutOfBoundsException

3 个答案: