// 1부터 10까지의 합
int sum = IntStream.rangeClosed(1,10).sum();
System.out.println(sum);
// 1부터 100까지의 합
System.out.println(IntStream.rangeClosed(1,100).sum());
// 1부터 1000까지의 합
System.out.println(IntStream.rangeClosed(1,1000).sum());
public static void main(String[] args) {
// 1부터 100까지의 짝수의 합
int sum = IntStream.rangeClosed(1, 100).filter(i -> i % 2 == 0).sum();
System.out.println(sum);
// 1부터 100까지의 홀수의 합
sum = IntStream.rangeClosed(1, 100).filter(i -> i % 2 == 1).sum();
System.out.println(sum);
}
// 짝수를 걸러내고 곱하기 2한 값을 출력
IntStream.rangeClosed(1, 10).filter(i -> i % 2 == 0).map(i -> i*2).forEach(System.out::println);
// 짝수를 걸러내고 곱하기 2한 값을 모두 더하기
int sum = IntStream.rangeClosed(1, 10).filter(i -> i % 2 == 0).map(i -> i*2).sum();
System.out.println(sum);
Grade.java
class Grade{
private String name;
private int kor;
private int eng;
private int math;
public Grade() {}
public Grade(String name, int kor, int eng, int math) {
this.name = name;
this.kor = kor;
this.eng = eng;
this.math = math;
}
public String getName() {
return name;
}
public int getKor() {
return kor;
}
public int getEng() {
return eng;
}
public int getMath() {
return math;
}
public void setName(String name) {
this.name = name;
}
public void setKor(int kor) {
this.kor = kor;
}
public void setEng(int eng) {
this.eng = eng;
}
public void setMath(int math) {
this.math = math;
}
}
public static void main(String[] args) {
List<Grade> gradeList = new ArrayList<Grade>();
gradeList.add(new Grade("김민식", 70,80,90));
gradeList.add(new Grade("김태우", 75,70,85));
gradeList.add(new Grade("김원중", 80,40,75));
// 리스트에 있는 사람들 출력하기
gradeList.stream().forEach(grade -> System.out.println(grade.getName()));
}
public static void main(String[] args) {
List<Grade> gradeList = new ArrayList<Grade>();
gradeList.add(new Grade("김민식", 70,80,90));
gradeList.add(new Grade("김태우", 75,70,85));
gradeList.add(new Grade("김원중", 80,40,75));
// 리스트에 있는 사람들 출력하기
gradeList.stream().forEach(
grade ->{
double avg = (grade.getKor() + grade.getEng() + grade.getMath()) / 3.0;
System.out.println(grade.getName() + " : " + avg);
}
);
}
package java_lambda_example_stream;
import java.util.ArrayList;
import java.util.List;
class Grade {
private String name;
private int kor;
private int eng;
private int math;
public Grade() {
}
public Grade(String name, int kor, int eng, int math) {
this.name = name;
this.kor = kor;
this.eng = eng;
this.math = math;
}
public String getName() {
return name;
}
public int getKor() {
return kor;
}
public int getEng() {
return eng;
}
public int getMath() {
return math;
}
public void setName(String name) {
this.name = name;
}
public void setKor(int kor) {
this.kor = kor;
}
public void setEng(int eng) {
this.eng = eng;
}
public void setMath(int math) {
this.math = math;
}
public double getAvg() {
return (kor + eng + math) / 3.0;
}
}
public class stream_example {
public static void main(String[] args) {
List<Grade> gradeList = new ArrayList<Grade>();
gradeList.add(new Grade("김민식", 70, 80, 90));
gradeList.add(new Grade("김태우", 75, 70, 85));
gradeList.add(new Grade("김원중", 80, 40, 75));
// 리스트에 있는 사람들 출력하기
gradeList.stream().forEach(grade -> {
// double avg = (grade.getKor() + grade.getEng() + grade.getMath()) / 3.0;
System.out.println(grade.getName() + " : " + grade.getAvg());
});
}
}
public static void main(String[] args) {
List<Grade> gradeList = new ArrayList<Grade>();
gradeList.add(new Grade("김민식", 70, 80, 90));
gradeList.add(new Grade("김태우", 75, 70, 85));
gradeList.add(new Grade("김원중", 80, 40, 75));
gradeList.add(new Grade("구자욱", 60, 50, 80));
// 김을 포함한 사람만 출력
gradeList.stream().filter(grade-> grade.getName().contains("김")).forEach(grade -> {
System.out.println(grade.getName() + " : " + grade.getAvg());
});
// 구를 포함한 사람은 제외
gradeList.stream().filter(grade-> !grade.getName().contains("구")).forEach(grade -> {
System.out.println(grade.getName() + " : " + grade.getAvg());
});
}
public static void main(String[] args) {
List<Grade> gradeList = new ArrayList<Grade>();
gradeList.add(new Grade("김민식", 70, 80, 90));
gradeList.add(new Grade("김태우", 75, 70, 85));
gradeList.add(new Grade("김원중", 80, 40, 75));
gradeList.add(new Grade("구자욱", 60, 50, 80));
gradeList.stream().filter(grade-> grade.getKor() >70).forEach(grade -> {
System.out.println(grade.getName() + " : " + grade.getAvg());
});
}