[英]Why is this code producing NullPointerException?
好吧,我有这个代码:
public void queryForId(){
String itemName = textField.getText().substring(7, textField.getText().length());
String br = System.getProperty("line.separator") + " ";
try {
once = false;
item_found = false;
BufferedReader bure = new BufferedReader(new FileReader("itemList.txt"));
while (true) {
String currentLine = bure.readLine();
String[] split = currentLine.split(" - ", 2);
if (split[1].equalsIgnoreCase(itemName)) {
String id = split[0].replace("\uFEFF", "");// removes the BOM.
textArea.append(br + "[Innovate] The ID(s) of the item '" + itemName + "' is : " + id + ".");
textField.setText("");
item_found = true;
} else {
if (!once && !item_found) {
textArea.append(br + "[Innovate] The Item cannot be found.");
textField.setText("");
once = true;
}
}
}
} catch(IOException z){
z.printStackTrace();
}
}
每当我使用此方法时,我都会得到所需的输出,但是它确实会产生nullpointer异常,并且编译器指向此行:
String[] split = currentLine.split(" - ", 2);
如果您要从BufferedReader中获取文本,则最好阅读教程并看一下示例,因为这种方法可以指示Stream何时完成,是否吐出一个空值,并且您的代码最好已准备就绪为了这种可能。 例如,
BufferedReader in = ....;
String inputLine = "";
// test for null here when reading in from the Reader
while ((inputLine = in.readLine()) != null) {
// use inputLine here
}
// close BufferedReader here, usually in a finally block
查看BufferedReader readLine()方法参考:
返回:包含行内容的String,不包含任何行终止字符;如果已到达流的末尾,则返回null
因此,当输入流的末尾到达时,此函数将返回null,您尝试在此方法上调用split()方法。
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