Belajar Java 8.

♠ Posted by Unknown in Android,J2EE at 8:50 PM

Berikut adalah contoh hal-hal baru yang bisa dilakukan dengan java 8.

A. Comparator, Sorting dengan class Collection

---
public class Test_1 {
    public static void main(String[] args) {
        List stringList = new ArrayList<>();
        stringList.add("fdasadQ");
        stringList.add("qfdasadQ");
        stringList.add("fwwdasadQ");
        stringList.add("sfdfsfdasadQ");
        stringList.add("4543fdasadQ");

        System.out.println(stringList);
//        Collections.sort(stringList); //

//        Collections.sort(stringList, (s1, s2) -> s1.compareTo(s2));        

Collections.sort(stringList, (s1, s2) -> s2.compareTo(s1)); 

//decending       

 System.out.println("setelah di sorting");
        System.out.println(stringList);
    }
}
result:
[fdasadQ, qfdasadQ, fwwdasadQ, sfdfsfdasadQ, 4543fdasadQ]
setelah di sorting
[sfdfsfdasadQ, qfdasadQ, fwwdasadQ, fdasadQ, 4543fdasadQ]
---

B. Functional Interface

public class Test_1 {
    public static void main(String[] args) {

        TesPrin tesPrin = () -> System.out.println("cetak terserah");
        TesPrinParam tesPrinParam = (ss) -> System.out.println("cetak "+ss);

        System.out.println("memanggil default method di interface >>> "+tesPrin.srqt(9));
        tesPrin.prin();
        tesPrinParam.prin("param");

        Operasi tambah = (int bilA,int bilB)-> bilA + bilB;
        Operasi kurang = (int bilA,int bilB)-> bilA - bilB;
        Operasi kali = (int bilA,int bilB)-> bilA * bilB;
        Operasi bagi = (int bilA,int bilB)-> bilA / bilB;

        System.out.println(kalkulator(3,4, tambah));
        System.out.println(kalkulator(3,4, kurang));
        System.out.println(kalkulator(3,4, kali));
        System.out.println(kalkulator(3,4, bagi));
    }


    interface TesPrin{
        void prin();

        default double srqt(double angka){
            return  Math.sqrt(angka);
        }
    }

    interface TesPrinParam{
        void prin(String param);
    }

    interface Operasi{
        int aksi(int bilA,int bilB);
    }

    public static int kalkulator(int bilA,int bilB, Operasi operasi){
        return operasi.aksi(bilA,bilB);
    }
}

result:
cetak terserah
cetak param
memanggil default method di interface >>> 3.0
cetak terserah
cetak param
7
-1
12
0

C. For Each

public class Test_1 {

    public static void main(String[] args) {

        List<Siswa> siswaList = new ArrayList<>();
        siswaList.add(new Siswa("Sucipto", "Pintar"));
        siswaList.add(new Siswa("Elnanda", "Pintar Sekali"));
        siswaList.add(new Siswa("Ujup", "1"));
        siswaList.add(new Siswa("Nazar", "1"));
        siswaList.add(new Siswa("Suseno", "XL"));
        System.out.println("forEach Siswa");
        siswaList.forEach(siswa -> System.out.println(siswa));
        System.out.println();
        siswaList.forEach(siswa -> {
            if (siswa!=null && siswa.getName().equals("Sucipto"))
                System.out.println(siswa);
        });
    }
}

class Siswa{

    String name;
    String kelas;
// get set

    @Override    public String toString() {
        return "Siswa{" +
                "name='" + name + '\'' +
                ", kelas='" + kelas + '\'' +
                '}';
    }
}

D. Stream

siswaList.stream()
        .filter(siswa -> siswa.getKelas().contains("Pintar"))
        .forEach(System.out::println);

List<Siswa> siswaList1 = siswaList.stream()
        .filter(siswa -> siswa.getKelas().contains("X"))
        .collect(Collectors.toList());
siswaList1.forEach(System.out::println);

steam grouping

Map<String, List<Siswa>> collect = siswaList.stream().collect(Collectors.groupingBy(Siswa::getName));
collect.forEach(
        (s, siswas) -> {
            System.out.println(s+"|"+siswas);
        }
);

E. Bla bla


F. Bla bla


G. Bla bla