使用snakeyaml将YAML转换为Java

当我试图打印出对象时，无法理解为什么在配置类的平台上会出现NullPointerException

以下是yaml文件：

platform:
  platformType: CVN
  hwVariant:
    canesVariant: HW
  hullNumber: XXX
  tri: INST

这是我的父对象类Configuration.java

public class Configuration {

private Platform platform;

public Configuration() {

}

public Platform getPlatform() {
    return platform;
}

public void setPlatform(Platform platform) {
    this.platform = platform;
}

@Override
public String toString() {
    return platform.toString();
}
}

这是我的Platform.java：

import java.util.Map;

public class Platform {

private String platformType;
private Map<String, String> hwVariant;
private String hullNumber;
private String tri;

public Platform() {

}

public String getPlatformType() {
    return platformType;
}

public Map<String, String> getHWVariant() {
    return hwVariant;
}

public String getHull() {
    return hullNumber;
}

public String getTri() {
    return tri;
}

public void setPlatformType(String platformType) {
    this.platformType = platformType;
}

public void setHWVariant(Map<String, String> hwVariant) {
    this.hwVariant = hwVariant;
}

public void setHullNumber(String hullNumber) {
    this.hullNumber = hullNumber;
}

public void setTri(String tri) {
    this.tri = tri;
}

@Override
public String toString() {
    return "platform: \n" +
           "  platformType: " + platformType + "\n" +
           "  hwVariant: " + hwVariant + "\n" +
           "  hullNumber: " + hullNumber + "\n" +
           "  tri: " + tri;
}

}

---

当我添加了内部嵌套hwVariant选项时，我似乎无法让它工作。如果我从yaml文件中删除hwVariant和canesVariant，尽管没有这些键值对，但效果很好。我缺少什么？

将类平台的字段“hwVariant”的Getter和Setter方法更改为以下方法

public Map<String, String> getHwVariant() {
    return hwVariant;
}

public void setHwVariant(Map<String, String> hwVariant) {
    this.hwVariant = hwVariant;
}

publicmap getHwVariant（）{
返回变量；
}
公共void setHwVariant（映射hwVariant）{
this.hwVariant=hwVariant；
}

SnakeYaml在内部使用jackson将yaml文档映射到java对象。Jackson在内部调用字段的getter和setter方法，所以它希望getter和setter采用标准形式

public Map<String, String> getHwVariant() {
    return hwVariant;
}

public void setHwVariant(Map<String, String> hwVariant) {
    this.hwVariant = hwVariant;
}