How to get specific object values from java <List> and convert to String Array

Question

I need your assistant and help in getting the values of an object in a Java and then to convert the output to String Array so I can pass it to a procedure. Here is my Java class:

public class PendingRequests  {

    private String requestDate; //Getter & Setter
    private String requestNo; //Getter & Setter
    private String employeeName; //Getter & Setter

}

And in the bean I am defining a List called "selectedRequests":

private List<PendingRequests> selectedRequests;

The selectedRequests is having values and I need to get the values of the requestNo from it and then convert it to String Array. With my attempts, I was only able to print them in the console by using the below code:

for(Object obj : selectedRequests){
    System.out.println("Obj = "+((PendingRequests)obj).getRequestNo());

But is it the correct way and what should I do next?

As a sidenote, you could just say for(PendingRequests obj : selectedRequests) if your ArrayList is declared with the Generic PendingRequests — SomeJavaGuy
– SomeJavaGuy, Commented Sep 17, 2015 at 13:04

score 10 · Accepted Answer · 2015-09-17 13:14:46Z

10

String[] requestNos = new String[selectedRequests.size()];

for (int i = 0; i < selectedRequests.size(); i++) {
    requestNos[i] = selectedRequests.get(i).getRequestNo();
}

And here is the Java 8 version of the same thing:

String[] requestNos = selectedRequests
                          .stream()
                          .map(r -> r.getRequestNo())
                          .toArray(String[]::new);

edited Sep 17, 2015 at 13:14

answered Sep 17, 2015 at 13:04

user21926

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2 Comments

user21926 Over a year ago

So that I have an index into the array, yes.

Jean Logeart Over a year ago

Kind of detail for the OP but what if the list is a LinkedList? Better: int i = 0; for(r : selectedRequests) { requestNos[i++] = r.getRequestNo(); } )

Andrei Amarfii · Accepted Answer · 2015-09-17 13:07:48Z

2

String[] stringArray = new String[selectedRequests.size()];
int i =0;
for(PendingRequests request: selectedRequests){
   stringArray[i] = request.getRequestNo();
   i++;
}

answered Sep 17, 2015 at 13:07

Andrei Amarfii

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Comments

Jean Logeart · Accepted Answer · 2015-09-17 15:03:32Z

2

In Java 8:

selectedRequests.stream()
                .map(PendingRequests::getRequestNo)
                .forEach(System.out::println)

edited Sep 17, 2015 at 15:03

answered Sep 17, 2015 at 13:09

Jean Logeart

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Comments

Panos · Accepted Answer · 2015-09-17 13:07:33Z

0

try:

String[] requestNos= new String[selectedRequests.size()];
for ( int i = 0; i < selectedRequests.size() ; i++ ) {
    PendingRequests pendingRequest = selectedRequests.get(i);
    requestNos[i] = pendingRequest.getRequestNo();
}

forgive me it throws any errors, I just wrote it on the fly. And don't forget to add null checks as this code will throw NullPointerException if something is null.

answered Sep 17, 2015 at 13:07

Panos

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Comments

Franck · Accepted Answer · 2015-09-17 13:18:58Z

0

Java 8 single line

String[] requestNos = selectedRequests.stream()
                      .map(
                          pr -> pr.getRequestNo()
                      )
                      .collect(Collectors.toList())
                      .toArray(new String[]{});

edited Sep 17, 2015 at 13:18

answered Sep 17, 2015 at 13:12

Franck

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