使用StringReader
时出现异常。创建对象时我解析的字符串是通过String.split
生成的,它给了我NullPointerException
。有任何建议如何解决这个问题?
以下是代码:
public static void main(String[] args) throws IOException {
// TODO code application logic here
int jmldoc = 5;
Hashmap hashsentences[][] = new Hashmap[5][100];
Docreader reader = new Docreader();
System.out.println(reader.doc[1]);
for (int i = 0; i < jmldoc; i++) {
int j = 0;
while (reader.sentences[i][j] != null) {
System.out.println(reader.sentences[i][j]);
j++;
String temp=reader.sentences[i][j];
StringReader h = new StringReader(temp);
}
}
}
和docreader类
public class Docreader {
public String sentences[][]=new String[5][100];
public String doc[]=new String[5];
public Docreader() throws IOException{
this.readdoc();
this.splittosentence();
}
public void readdoc() throws IOException {
for (int i = 0; i < 5; i++) {
String temp = new String();
temp = Docreader.readFile("datatrain/doc" + (i + 1) + ".txt");
this.doc[i] = temp;
}
}
public void splittosentence() {
for (int i = 0; i < 5; i++) {
String temp[];
temp = doc[i].split("\\.");
for(int j=0;j<temp.length;j++){
sentences[i][j]=temp[j];
}
}
}
private static String readFile(String fileName) throws IOException {
try (BufferedReader br = new BufferedReader(new FileReader(fileName))) {
StringBuilder sb = new StringBuilder();
String line = br.readLine();
while (line != null) {
sb.append(line);
sb.append("\n");
line = br.readLine();
}
return sb.toString();
}
}
}
例外:
Exception in thread "main" java.lang.NullPointerException
at java.io.StringReader.<init>(StringReader.java:50)
at stki_d_8_final.STKI_D_8_Final.main(STKI_D_8_Final.java:45)
Java结果:1
当我检查StringReader
类中的第50行时,它包含
this.length = s.length();
答案 0 :(得分:4)
在这部分代码中:
while (reader.sentences[i][j] != null) {
System.out.println(reader.sentences[i][j]);
j++;
String temp=reader.sentences[i][j];
StringReader h = new StringReader(temp);
}
您正在使用j++
,因此j
的值增加1,那么您就拥有以下代码:
String temp=reader.sentences[i][j];
由于数组中的新条目与null
不同,因此尚未评估,因此它可能包含null
值,该值已分配给temp
并因此初始化StringReader
null
值作为参数。
使用它构建j
后,解决问题的方法是增加StringReader
。此外,如果ArrayIndexOutOfBoundsException
的所有值都不是reader.sentences[i]
,则在当前形式下,此代码也可能会抛出null
。这将是上述代码的解决方案:
while (j < reader.sentences[i].length && reader.sentences[i][j] != null) {
System.out.println(reader.sentences[i][j]);
String temp=reader.sentences[i][j];
StringReader h = new StringReader(temp);
j++;
}
答案 1 :(得分:3)
在这部分代码中:
while (reader.sentences[i][j] != null) {
System.out.println(reader.sentences[i][j]);
j++;
String temp=reader.sentences[i][j];
StringReader h = new StringReader(temp);
}
你恰当地确保reader.sentences[i][j] != null
,然后你增加j(j++
)并且不进行空检查。