Javapoet: $T to refer types

$T is used to refer the types.

 

Example 1: mainMethodSpecBuilder.addStatement("$T date = today()", Date.class);

Above snippet generates below statement.

Date date = today();

 

Example 2: Define a method to get today date.

MethodSpec.Builder todaySpecBuilder = MethodSpec.methodBuilder("today");
todaySpecBuilder.returns(Date.class);
todaySpecBuilder.addStatement("return new $T()", Date.class);
todaySpecBuilder.addModifiers(Modifier.PRIVATE, Modifier.STATIC);

 

Above snippet generates below snippet.

 

private static Date today() {

  return new Date();

}

 

Find the below working application.

 

ReferATypeDemo.java

package com.sample.app;

import java.io.IOException;
import java.util.Date;

import javax.lang.model.element.Modifier;

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

public class ReferATypeDemo {

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

    MethodSpec.Builder todaySpecBuilder = MethodSpec.methodBuilder("today");
    todaySpecBuilder.returns(Date.class);
    todaySpecBuilder.addStatement("return new $T()", Date.class);
    todaySpecBuilder.addModifiers(Modifier.PRIVATE, Modifier.STATIC);

    MethodSpec todayMethodSpec = todaySpecBuilder.build();

    MethodSpec.Builder mainMethodSpecBuilder = MethodSpec.methodBuilder("main");
    mainMethodSpecBuilder.addModifiers(Modifier.PUBLIC, Modifier.STATIC);
    mainMethodSpecBuilder.returns(void.class);
    mainMethodSpecBuilder.addParameter(String[].class, "args");

    mainMethodSpecBuilder.addCode("\n");
    mainMethodSpecBuilder.addStatement("$T date = today()", Date.class);
    mainMethodSpecBuilder.addStatement("System.out.println(date)");
    mainMethodSpecBuilder.addCode("\n");

    MethodSpec mainMethodSpec = mainMethodSpecBuilder.build();

    String className = "HelloWorld";
    TypeSpec.Builder classSpecBuilder = TypeSpec.classBuilder(className);
    classSpecBuilder.addModifiers(Modifier.PUBLIC, Modifier.FINAL);
    classSpecBuilder.addMethod(mainMethodSpec);
    classSpecBuilder.addMethod(todayMethodSpec);
    TypeSpec helloWorldTypeSpec = classSpecBuilder.build();

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

    javaFile.writeTo(System.out);
  }

}

Generated snippet

package com.sample.app;

import java.lang.String;
import java.util.Date;

public final class HelloWorld {
  public static void main(String[] args) {

    Date date = today();
    System.out.println(date);

  }

  private static Date today() {
    return new Date();
  }
}

 

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