多维的arraylist不工作 [英] Multidimentional arraylist not working

问题描述

我有一些数据，我想要的是多维数组列表的格式。我使用JSOUP库从我的网站获取这些数据。我使用String Builder检查结果以确保数据实际到来。

I have some data which I want in the format of multidimensional array list. I am getting this data from my website using JSOUP library. I checked the result using String Builder to make sure that data is actually coming.

ArrayList<string> attendancetd;
ArrayList<ArrayList<string>> attendancerow;
attendancetd = new ArrayList<string>();
attendancerow = new ArrayList<ArrayList<string>>();
for (Element attendanceTablerow : attedanceTableRows ){
    Elements tds = attendanceTablerow.select("td");
    for (Element td : tds){
        stringBuffer.append(td.text()+"*");
        attendancetd.add(td.text());
    }
    attendancerow.add(new ArrayList<string>(attendancetd));
    //attendancerow.add(attendancetd);
    attendancetd.clear();
    stringBuffer.append("\n");
}
//System.out.println(String.valueOf(stringBuffer));
int index=0;
for(ArrayList<string> row : attendancerow){
    Log.w("aa","(Row"+index+") " + row.get(0) + " | "+row.get(1)+ " | "+row.get(2));
    index++;
}

这是logcat



引起：java.lang.IndexOutOfBoundsException：索引0无效，大小为0

（在Log.w的行）



我尝试过：



我试图关注Android - Android - 使用多维字符串数组 - 堆栈溢出 [ ^ ]使用多维字符串数组



I还检查我的logcat错误

Here's the logcat

Caused by: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
(at Log.w's Line)

What I have tried:

I tried to follow Android - Android - Working with Multidimensional String Arrays - Stack Overflow[^] Working with Multidimensional String Arrays

I also check my logcat error here

推荐答案

当你不理解你的代码在做什么或为什么它做它的作用时，答案是 debugger 。

使用调试器查看代码正在执行的操作。只需设置断点并查看代码执行情况，调试器允许您逐行执行第1行并在执行时检查变量，这是一个令人难以置信的学习工具。

Debugger - 维基百科，免费的百科全书 [ ^ ]

http://docs.oracle.com/javase/7/docs/technotes/tools/windows/jdb.html [ ^ ]

https://www.jetbrains.com/idea/help/debugging-your-first-java-application.html [ ^ ]

调试器是这里向您展示您的代码正在做什么，您的任务是与它应该做什么进行比较。

调试器中没有魔法，它没有找到错误，它只是帮助您。当代码没有达到预期的效果时，你就会接近一个错误。

When you don't understand what your code is doing or why it does what it does, the answer is debugger.
Use the debugger to see what your code is doing. Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute, it is an incredible learning tool.
Debugger - Wikipedia, the free encyclopedia[^]
http://docs.oracle.com/javase/7/docs/technotes/tools/windows/jdb.html[^]
https://www.jetbrains.com/idea/help/debugging-your-first-java-application.html[^]
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't find bugs, it just help you to. When the code don't do what is expected, you are close to a bug.

这篇关于多维的arraylist不工作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！