[英]Parsing a JSON file in Java using GSON
我試圖在 Java 中使用 GSON 解析這個 JSON 文件,但我遇到了一些困難。
{"group": [
{
"name": "Team1 Student2",
"email": "ctc-t1-s2",
"contribution": {
"score": 16.6,
"comment": "From 'Team1 Student2' about 'Team1 Student2'\nAnd they said, \"You'll never get it done!\""
}
}
,{
"name": "Team1 Student4",
"email": "mmi-t1-s4",
"contribution": {
"score": 0.4,
"comment": "From 'Team1 Student2' about 'Team1 Student4'\nAnd they said, \"You'll never get it done!\""
}
}
,{
"name": "Team1 Student3",
"email": "pco-t1-s3",
"contribution": {
"score": 39.1,
"comment": "From 'Team1 Student2' about 'Team1 Student3'\nAnd they said, \"You'll never get it done!\""
}
}
,{
"name": "Team1 Student1",
"email": "eyr-t1-s1",
"contribution": {
"score": 23.9,
"comment": "From 'Team1 Student2' about 'Team1 Student1'\nAnd they said, \"You'll never get it done!\""
}
}],"confidential_comments": "That's all! It was \"fun\"! (said Team1 Student2)\nDon't forget: Bring your towel \\ the cake is a lie."}
現在我有三個班級,其中一個是小組班級:
public class Group {
private List<Student> group[];
public Group(List<Student> students[]){
this.group = students;
}
public void setStudents(List<Student> students[]) {
this.group = students;
}
public List<Student>[] getStudents() {
return group;
}
@Override
public String toString() {
return "Group{" +
"students=" + Arrays.toString(group) +
'}';
}
}
以及學生班級:
public class Student {
private String name;
private String sfu_email;
public Student(String name, String email){
this.name = name;
this.sfu_email = email;
}
public String getName() {
return name;
}
public String getEmail(){
return sfu_email;
}
public void setEmail(String email) {
this.sfu_email = email;
}
public void setName(String name) {
this.name = name;
}
public String toString(){
return getName() + " " + getName();
}
}
在我的主函數中,當我運行它時,我最終打印了一個 NULL 對象。
Gson gson = new Gson();
JsonParser jsonParser = new JsonParser();
try(Reader reader = new FileReader("FILE PATH")) {
JsonElement jsonObject = jsonParser.parse((reader));
System.out.println(jsonObject);
Group students = gson.fromJson(jsonObject, Group.class);
System.out.println(students);
Student student = gson.fromJson(jsonObject, Student.class);
System.out.println(student);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
我想知道您如何能夠解析輸入文件,以便將 JSON 字符串放入對象或對象列表中? 抱歉問了這么長的問題。
我認為出現問題的地方是在您的 JSON group
中已經是一個List<Student>
,但是您正在嘗試從 gson 檢索組對象。 我認為你需要的是一個不同的對象,比如Reader
或這樣的Response
:
class Response {
private Group group;
}
然后執行以下操作:
Response response = gson.fromJson(jsonObject, Response.class);
Group = response.getGroup();
請注意,要使 GSON 正常工作,類中的字段名稱需要與 JSON 匹配。 (所以sfu_email
的Student
應該讀email
按了JSON)。
希望這可以幫助
Group
類包含List<Student>
,同樣不需要在group
變量名稱的末尾添加[]
。
public class Group {
private List<Student> group;
public void setStudents(List<Student> students) {
this.group = students;
}
public List<Student> getStudents() {
return group;
}
@Override
public String toString() {
return "Group [group=" + group + "]";
}
}
確保類中的字段名稱需要與 JSON 匹配。
public class Student {
private String name;
private String email; //sfu_email changed to email
public Student(String name, String email) {
this.name = name;
this.email = email;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@Override
public String toString() {
return "Student [name=" + name + ", email=" + email + "]";
}
嘗試使用上述解決方案。
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