Using ParameterizedTypeName , and WildcardTypeName we can spcify wildcard types parameters.
Step 1: Define ParameterSpec instance using WildcardTypeName.
ParameterizedTypeName parameterizedTypeName1 = ParameterizedTypeName.get(ClassName.get(Class.class),
WildcardTypeName.subtypeOf(Number.class));
ParameterSpec parameterSpec1 = ParameterSpec.builder(parameterizedTypeName1, "param1", Modifier.FINAL).build();
Step 2: Add ParameterSpec instance to a method as parameter.
MethodSpec demoMethod = MethodSpec.methodBuilder("demo").addModifiers(Modifier.PUBLIC)
.addParameter(parameterSpec1).addParameter(parameterSpec2).build();
Find the below working application.
WildCardTypeParameters.java
package com.sample.app;
import java.io.IOException;
import java.util.List;
import javax.lang.model.element.Modifier;
import com.squareup.javapoet.ClassName;
import com.squareup.javapoet.JavaFile;
import com.squareup.javapoet.MethodSpec;
import com.squareup.javapoet.ParameterSpec;
import com.squareup.javapoet.ParameterizedTypeName;
import com.squareup.javapoet.TypeSpec;
import com.squareup.javapoet.WildcardTypeName;
public class WildCardTypeParameters {
public static void main(String args[]) throws IOException {
ParameterizedTypeName parameterizedTypeName1 = ParameterizedTypeName.get(ClassName.get(Class.class),
WildcardTypeName.subtypeOf(Number.class));
ParameterSpec parameterSpec1 = ParameterSpec.builder(parameterizedTypeName1, "param1", Modifier.FINAL).build();
ParameterizedTypeName parameterizedTypeName2 = ParameterizedTypeName.get(ClassName.get(Class.class),
WildcardTypeName.subtypeOf(List.class));
ParameterSpec parameterSpec2 = ParameterSpec.builder(parameterizedTypeName2, "param2", Modifier.FINAL).build();
MethodSpec demoMethod = MethodSpec.methodBuilder("demo").addModifiers(Modifier.PUBLIC)
.addParameter(parameterSpec1).addParameter(parameterSpec2).build();
TypeSpec helloWorldTypeSpec = TypeSpec.classBuilder("Test").addMethod(demoMethod).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.io.IOException;
import java.util.List;
import javax.lang.model.element.Modifier;
import com.squareup.javapoet.ClassName;
import com.squareup.javapoet.JavaFile;
import com.squareup.javapoet.MethodSpec;
import com.squareup.javapoet.ParameterSpec;
import com.squareup.javapoet.ParameterizedTypeName;
import com.squareup.javapoet.TypeSpec;
import com.squareup.javapoet.WildcardTypeName;
public class WildCardTypeParameters {
public static void main(String args[]) throws IOException {
ParameterizedTypeName parameterizedTypeName1 = ParameterizedTypeName.get(ClassName.get(Class.class),
WildcardTypeName.subtypeOf(Number.class));
ParameterSpec parameterSpec1 = ParameterSpec.builder(parameterizedTypeName1, "param1", Modifier.FINAL).build();
ParameterizedTypeName parameterizedTypeName2 = ParameterizedTypeName.get(ClassName.get(Class.class),
WildcardTypeName.subtypeOf(List.class));
ParameterSpec parameterSpec2 = ParameterSpec.builder(parameterizedTypeName2, "param2", Modifier.FINAL).build();
MethodSpec demoMethod = MethodSpec.methodBuilder("demo").addModifiers(Modifier.PUBLIC)
.addParameter(parameterSpec1).addParameter(parameterSpec2).build();
TypeSpec helloWorldTypeSpec = TypeSpec.classBuilder("Test").addMethod(demoMethod).build();
String packageName = "com.sample.app";
JavaFile javaFile = JavaFile.builder(packageName, helloWorldTypeSpec).build();
javaFile.writeTo(System.out);
}
}
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