有如下Student 对象, private String name; private int age; private int score; private String classNum; 其中,classNum
package homework003; import java.util.ArrayList; import java.util.List; public class Text { public static void main(String[] args) { List<Student> list = new ArrayList<>(); list.add(new Student("Tom",18,100,"class05")); list.add(new Student("Jerry",22,70,"class04")); list.add(new Student("Owen",25,90,"class05")); list.add(new Student("Jim",30,80,"class05")); list.add(new Student("Steve",28,66,"class06")); list.add(new Student("Kevin",24,100,"class04")); int sum = 0; for(int i =0;i<list.size();i++) { sum+=list.get(i).getAge(); } System.out.println("所有学生的平均年龄为:"+sum/list.size()); int num1=0; int num2=0; int num3=0; int score1=0; int score2=0; int score3=0; for(int i =0;i<list.size();i++) { Student st =list.get(i); if(st.getClassNum()=="class04") { num1++; score1+=st.getScore(); } else if(st.getClassNum()=="class05") { num2++; score2+=st.getScore(); } else { num3++; score3+=st.getScore(); } } System.out.println("class04的平均分:"+(score1/num1)); System.out.println("class05的平均分:"+(score2/num2)); System.out.println("class06的平均分:"+(score3/num3)); } }
package homework003; public class Student { private String name; private int age; private int score; private String classNum; public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public int getScore() { return score; } public void setScore(int score) { this.score = score; } public String getClassNum() { return classNum; } public void setClassNum(String classNum) { this.classNum = classNum; } public Student(String name, int age, int score, String classNum) { super(); this.name = name; this.age = age; this.score = score; this.classNum = classNum; } public Student() { super(); } @Override public String toString() { return "Student [name=" + name + ", age=" + age + ", score=" + score + ", classNum=" + classNum + "]"; } }