Builder构造函数必须具有必需的参数。因此，在您的情况下，如果userId，clientId和parameterMap是强制性的，则我们将得到以下内容：
public final class ModelInput { private long userid; private long clientid; private long timeout = 500L; private Preference pref; private boolean debug; private Map<String, String> parameterMap; public ModelInput(Builder builder) { this.userid = builder.userId; this.clientid = builder.clientId; this.pref = builder.preference; this.parameterMap = builder.parameterMap; this.timeout = builder.timeout; this.debug = builder.debug; } public static class Builder { private long userId; private long clientId; private Preference preference; private boolean debug; private Map<String, String> parameterMap; public Builder(long userId, long clientId, Map<String, String> parameterMap) { this.userId = userId; this.clientId = clientId; this.parameterMap = parameterMap; } public Builder preference(Preference preference) { this.preference = preference; return this; } public Builder debug(boolean debug) { this.debug = debug; return this; } public Builder timeout(long timeout) { this.timeout = timeout; return this; } ... public ModelInput build() { return ModelInput(this); } } // ModelInput getters / setters}这是如何使用构建器类的方法：
String paramMap = new HashMap<String, String>();paramMap.put("attribute", "segmentation");ModelInput.Builder builder = new ModelInput.Builder(109739281L, 20L, paramMap);builder.preference(Preference.SECONDARY).timeout(1000L).debug(true);ModelInput modelInput = builder.build();希望这可以帮助 ：）
