Java ArrayList排序异常:ArrayIndexOutOfBoundsException

Question

在我的Java应用程序中，我有一个扩展ArrayList并实现TableModel的类MyFileList。MyFile类

当我单击在gui中对列进行排序时，我会收到一个异常，并且列表只剩下一半排序。

Exception in thread "AWT-EventQueue-2" java.lang.ArrayIndexOutOfBoundsException: -1
    at java.util.ArrayList.elementData(Unknown Source)
    at java.util.ArrayList.get(Unknown Source)
    at com.example.smdb.MyFileList.getValueAt(MyFileList.java:321)
    at com.example.util.MyObjectListComparator.compare(MyObjectListComparator.java:97)
    at java.util.TimSort.mergeHi(Unknown Source)
    at java.util.TimSort.mergeAt(Unknown Source)
    at java.util.TimSort.mergeForceCollapse(Unknown Source)
    at java.util.TimSort.sort(Unknown Source)
    at java.util.Arrays.sort(Unknown Source)
    at java.util.ArrayList.sort(Unknown Source)
    at java.util.Collections.sort(Unknown Source)
    at com.example.gui.MyTableSorter.sort(MyTableSorter.java:73)
    at com.example.gui.MyTableSorter.sortByColumn(MyTableSorter.java:93)
    at com.example.gui.PreservableColSizeJTable$PersistentJTableHeader.mouseClicked(PreservableColSizeJTable.java:935)

MyTableSorter排序方法：

public void sort(int column) {
        if(model instanceof List){
           Collections.sort ((List)model, new MyObjectListComparator((List)model, column, ascending));
        }
    }

MyObjectListComparator比较方法：

public int compare(Object obj, Object obj1) {
    int result = 0;
    int row = this.filelist.indexOf(obj);
    int row1 = this.filelist.indexOf(obj1);
    Object value = ((MyFileList) this.filelist).getValueAt(row, column);
    value = ((MyFile.FileAttr) value).getAttrValue();
    Object value1 = ((MyFileList) this.filelist).getValueAt(row1, column);
    value1 = ((MyFile.FileAttr) value1).getAttrValue();
    result = compareAttr(value, value1);
    return result;
}

MyFile等于方法：

public boolean equals(Object obj) {
    if (obj instanceof MyFile) {
        if (this.getAttribute(FILE_ID) != null) {
            return this.getAttribute(FILE_ID).equals(((MyFile) obj).getAttribute(FILE_ID));
        } 
    }
    return false;
}

调试后，我看到compare方法中的this.filelist.indexOf(obj)正在返回-1。如果我发现这个异常并让它继续排序，那么我的列表中会出现一些重复的项目和一些丢失的项目。

我在TimSort中发现了一些听起来非常相似的bug引用，所以我尝试了useLegacySortMerge选项。这给了我相同的行为，但堆栈跟踪略有不同，所以不幸的是，这看起来并不是问题所在。

Exception in thread "AWT-EventQueue-2" java.lang.ArrayIndexOutOfBoundsException: -1
    at java.util.ArrayList.elementData(Unknown Source)
    at java.util.ArrayList.get(Unknown Source)
    at com.example.smdb.MyFileList.getValueAt(MyFileList.java:321)
    at com.example.util.MyObjectListComparator.compare(MyObjectListComparator.java:97)
    at java.util.Arrays.mergeSort(Unknown Source)
    at java.util.Arrays.mergeSort(Unknown Source)
    at java.util.Arrays.mergeSort(Unknown Source)
    at java.util.Arrays.legacyMergeSort(Unknown Source)
    at java.util.Arrays.sort(Unknown Source)
    at java.util.ArrayList.sort(Unknown Source)
    at java.util.Collections.sort(Unknown Source)
    at com.example.gui.MyTableSorter.sort(MyTableSorter.java:73)
    at com.example.gui.MyTableSorter.sortByColumn(MyTableSorter.java:93)
    at com.example.gui.PreservableColSizeJTable$PersistentJTableHeader.mouseClicked(PreservableColSizeJTable.java:935)

这几天来一直让我抓狂。有什么见解吗？

Answer 1

只是一个想法：您可以处理在文件列表中找不到row和row1的情况，假设两者的缺席是等效的，并且缺席比任何存在都"少"。如果不起作用，则反转1和-1。

public int compare(Object obj, Object obj1) {
    int result = 0;
    int row = this.filelist.indexOf(obj);
    int row1 = this.filelist.indexOf(obj1);
    if(row == -1){
        if(row1 == -1){
            return 0;
        }
        return -1;
    }else if(row1 == -1){
        return 1;
    }
    Object value = ((MyFileList) this.filelist).getValueAt(row, column);
    value = ((MyFile.FileAttr) value).getAttrValue();
    Object value1 = ((MyFileList) this.filelist).getValueAt(row1, column);
    value1 = ((MyFile.FileAttr) value1).getAttrValue();
    result = compareAttr(value, value1);
    return result;
}