get list of String from array of objects with concat in java 8 - java-8

Question

I have 2 java Classes :-
class A {
String title;
B classb;
}
class B {
String name;
}
Now I have List of class A and the result which I am looking for :-
List of {a.title +" "+a.classb.name}

Answer 1

Using java 8 stream API:
A.java
public class A {
private String title;
private B classB;
public A(String title, B classB) {
this.title = title;
this.classB = classB;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public B getClassB() {
return classB;
}
public void setClassB(B classB) {
this.classB = classB;
}
#Override
public String toString() {
return "A{" +
"title='" + title + '\'' +
", classB=" + classB +
'}';
}
B.java
public class B {
private String name;
public B(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#Override
public String toString() {
return "B{" +
"name='" + name + '\'' +
'}';
}
Test.java
public class Test {
public static void main(String[] args) {
A a1 = new A("titleA1",new B("B1"));
A a2 = new A("titleA2",new B("B2"));
A a3 = new A("titleA3",new B("B3"));
A a4 = new A("titleA4",new B("B4"));
List<A> list = Arrays.asList(a1,a2,a3,a4);
List<String> updatedList = list.stream().map(x -> x.getTitle() + " " + x.getClassB().getName()).collect(Collectors.toList());
System.out.println(updatedList);
}
}
Output::
[titleA1 B1, titleA2 B2, titleA3 B3, titleA4 B4]

Answer 2

From your question, I only able to understand that you want to convert your Collection of Class A to make Collection of String (i.e. value should be like this a.title +" "+a.classb.name)
What you are looking for as follows
list.stream()
.map(a-> String.join(" ", a.title, a.classb.name))
.collect(Collectors.toList())
.forEach(System.out::println);