java - 静态工厂 builder 的麻烦

Question

需要创建数量不详的对象，我尝试创建一个构建器来执行此操作。一切都很好，直到我意识到我的构建器创建的所有对象的属性都具有相同的值。

所以当我调用构建器时:

ValidationHelper v = new ValidationHelper.HelperBuilder()
        .addHelper("ICAO Identifier", icaoIdentifier, rulesICAO)
        .addHelper("Long Name", longName, rulesLongName)
        .build();

...我将有 2 个对象，它们的属性将具有构建器被要求创建的最后一个对象的值。

首先，工厂 build 者是否是谨慎的做法？其次，我的构建器是否还有救？

builder :

public class ValidationHelper {

    private static ArrayList<HelperBuilder> validatorHelpers = new ArrayList();


    public static class HelperBuilder {

        private String txtFieldName;
        private String txtFieldValue;

        private List<Integer> valCodes = new ArrayList<Integer>();

        private ArrayList<HelperBuilder> innerValidatorHelpers = new ArrayList<HelperBuilder>();

        public HelperBuilder() {}

        public final HelperBuilder addHelper(String txtFieldName, String txtFieldValue, int[] validationCodes) {

            this.txtFieldName = txtFieldName;
            this.txtFieldValue = txtFieldValue;
            for( int i = 0; i < validationCodes.length; i++ ){
                getValCodes().add((Integer) validationCodes[i]);
            }

            innerValidatorHelpers.add(this);
            return this;
        }

        public final ValidationHelper build() {
            return new ValidationHelper(this);
        }

        public String getTxtFieldName() {
            return txtFieldName;
        }

        public String getTxtFieldValue() {
            return txtFieldValue;
        }

        public List<Integer> getValCodes() {
            return valCodes;
        }
    }//end HelperBuilder

    private ValidationHelper(HelperBuilder helperBuilder) {
        validatorHelpers = helperBuilder.innerValidatorHelpers;
    }

    public void setHelpers(ArrayList validatorHelpers) {
        validatorHelpers = validatorHelpers;
    }

    public ArrayList getHelpers() {
        return validatorHelpers;
    }
}

编辑/修复:

因此，就其值(value)而言，这是修改后的构建器。它需要另一个构造函数来正确初始化它应该构建的实例。

public class ValidationHelper {

    private static ArrayList<HelperBuilder> validatorHelpers = new ArrayList();

    public static class HelperBuilder {

        private String txtFieldName;
        private String txtFieldValue;

        private List<Integer> valCodes = new ArrayList<Integer>();

        private ArrayList<HelperBuilder> innerValidatorHelpers = new ArrayList<HelperBuilder>();

        public HelperBuilder() {}
        public HelperBuilder(String txtFieldName, String txtFieldValue, int[] validationCodes) {

            this.txtFieldName = txtFieldName;
            this.txtFieldValue = txtFieldValue;

            for (int i = 0; i < validationCodes.length; i++) {
                valCodes.add((Integer) validationCodes[i]);
            }

        }

        public final HelperBuilder addHelper(String txtFieldName, String txtFieldValue, int[] validationCodes) {
            innerValidatorHelpers.add( new HelperBuilder(txtFieldName, txtFieldValue, validationCodes) );
            return this;
        }

        public final ValidationHelper build() {
            return new ValidationHelper(this);
        }

        public String getTxtFieldName() {
            return txtFieldName;
        }

        public String getTxtFieldValue() {
            return txtFieldValue;
        }

        public List getValCodes() {
            return valCodes;
        }
    }//end HelperBuilder

    private ValidationHelper(HelperBuilder helperBuilder) {
        validatorHelpers = helperBuilder.innerValidatorHelpers;
    }

    public ArrayList getHelpers() {
        return validatorHelpers;
    }
}

Answer 1

每次你只是覆盖中的值

private String txtFieldName;
private String txtFieldValue;

最后一个获胜。所以你在这里只创建 1 个 HelperInstance

ValidationHelper v = new ValidationHelper.HelperBuilder()

每次调用 addHelper() 时，字段名称和值都会被覆盖。但是您需要为每个“配置”创建一个实例。所以 addHelper 应该创建一个新的 Instance 并将其添加到

private ArrayList<HelperBuilder> innerValidatorHelpers = ...;