无法解决这个问题。尝试将String对象添加到ArrayList时出现空指针异常。问题是,我相信我已经正确地初始化了“temp” ArrayList。请帮忙。
void initialConbinations(String[] headers) {
//Dataset is SN,FN,RN,PN
//Map the headers to the appropriate portions
String[] newHeaders = {"SN,high", "SN,medium", "SN,low", "FN,high", "FN,medium", "FN,low", "RN,high", "RN,medium", "RN,low"};
List<List> assRuleHeaders = new ArrayList<List>();
ArrayList<String> temp = new ArrayList<String>();
//Use bitwise shifting to do the rest
int k = 0, l = 0;
for (int i = 1; i < 511; i++) {
for (int j = 0; j < 9; j++) {
l = i;
k = (l >> j) & 0x00000001;
if (k == 1) {
System.out.println(k + " , " + i + " , " + j);
System.out.println(newHeaders[j]);
temp.add(newHeaders[j]); //Getting a Null Pointer Exception here
}
}
assRuleHeaders.add(temp);
temp = null;
}
for (int i = 0; i < assRuleHeaders.size(); i++) {
this.printArray(assRuleHeaders.get(i));
}
}