Javapoet: enum: override super class methods of enum value

Using 'TypeSpec.anonymousClassBuilder', you can override the super class methods of enum value.

 

EnumDemo2.java

package com.sample.app;

import java.io.IOException;

import javax.lang.model.element.Modifier;

import com.squareup.javapoet.FieldSpec;
import com.squareup.javapoet.JavaFile;
import com.squareup.javapoet.MethodSpec;
import com.squareup.javapoet.TypeName;
import com.squareup.javapoet.TypeSpec;

public class EnumDemo2 {

  public static void main(String args[]) throws IOException {

    TypeSpec helloWorldTypeSpec = TypeSpec.enumBuilder("MONTH").addModifiers(Modifier.PUBLIC)
        .addEnumConstant("JANUARY",
            TypeSpec.anonymousClassBuilder("$1L, \"$2L\"", 1, "31 Days")
                .addMethod(MethodSpec.methodBuilder("toString").addAnnotation(Override.class)
                    .addModifiers(Modifier.PUBLIC).addStatement("return $S", "I am first month in the year.....!")
                    .returns(String.class).build())
                .build())
        .addEnumConstant("FEBRUARY", TypeSpec.anonymousClassBuilder("$1L, \"$2L\"", 2, "28 or 29 Days").build())
        .addEnumConstant("MARCH", TypeSpec.anonymousClassBuilder("$1L, \"$2L\"", 3, "31 Days").build())
        .addEnumConstant("APRIL", TypeSpec.anonymousClassBuilder("$1L, \"$2L\"", 4, "30 Days").build())
        .addEnumConstant("MAY", TypeSpec.anonymousClassBuilder("$1L, \"$2L\"", 5, "31 Days").build())
        .addEnumConstant("JUNE", TypeSpec.anonymousClassBuilder("$1L, \"$2L\"", 6, "30 Days").build())
        .addEnumConstant("JULY", TypeSpec.anonymousClassBuilder("$1L, \"$2L\"", 7, "31 Days").build())
        .addEnumConstant("AUGUST", TypeSpec.anonymousClassBuilder("$1L, \"$2L\"", 8, "31 Days").build())
        .addEnumConstant("SEPTEMBER", TypeSpec.anonymousClassBuilder("$1L, \"$2L\"", 9, "30 Days").build())
        .addEnumConstant("OCTOBER", TypeSpec.anonymousClassBuilder("$1L, \"$2L\"", 10, "31 Days").build())
        .addEnumConstant("NOVEMBER", TypeSpec.anonymousClassBuilder("$1L, \"$2L\"", 11, "30 Days").build())
        .addEnumConstant("DECEMBER", TypeSpec.anonymousClassBuilder("$1L, \"$2L\"", 12, "31 Days").build())
        .addField(FieldSpec.builder(TypeName.INT, "seqNum").build())
        .addField(FieldSpec.builder(String.class, "message").build())
        .addMethod(MethodSpec.constructorBuilder().addParameter(TypeName.INT, "seqNum")
            .addParameter(String.class, "message").addStatement("this.$N = $N", "seqNum", "seqNum")
            .addStatement("this.$N = $N", "message", "message").build())
        .build();

    String packageName = "com.sample.app";
    JavaFile javaFile = JavaFile.builder(packageName, helloWorldTypeSpec).build();

    javaFile.writeTo(System.out);
  }

}

Generated code

package com.sample.app;

import java.lang.Override;
import java.lang.String;

public enum MONTH {
  JANUARY(1, "31 Days") {
    @Override
    public String toString() {
      return "I am first month in the year.....!";
    }
  },

  FEBRUARY(2, "28 or 29 Days"),

  MARCH(3, "31 Days"),

  APRIL(4, "30 Days"),

  MAY(5, "31 Days"),

  JUNE(6, "30 Days"),

  JULY(7, "31 Days"),

  AUGUST(8, "31 Days"),

  SEPTEMBER(9, "30 Days"),

  OCTOBER(10, "31 Days"),

  NOVEMBER(11, "30 Days"),

  DECEMBER(12, "31 Days");

  int seqNum;

  String message;

  MONTH(int seqNum, String message) {
    this.seqNum = seqNum;
    this.message = message;
  }
}

 

 

  

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