定义一个学生类student，成员变量包括姓名，性别，年龄，语文成绩，数学成绩和英语成绩，成员方法包括get XXX方法，set XXX方法，求总分和平均分，定义一个测试类student test，创建一个student对象，对其进行赋值并计算总分与平均分

首先，我们可以定义一个名为`Student`的类，用于表示学生的信息：

public class Student {
    private String name;
    private String gender;
    private int age;
    private double chineseScore;
    private double mathScore;
    private double englishScore;

    // 构造函数
    public Student(String name, String gender, int age, double chineseScore, double mathScore, double englishScore) {
        this.name = name;
        this.gender = gender;
        this.age = age;
        this.chineseScore = chineseScore;
        this.mathScore = mathScore;
        this.englishScore = englishScore;
    }

    // 获取方法
    public String getName() { return name; }
    public String getGender() { return gender; }
    public int getAge() { return age; }
    public double getChineseScore() { return chineseScore; }
    public double getMathScore() { return mathScore; }
    public double getEnglishScore() { return englishScore; }

    // 设置方法
    public void setName(String name) { this.name = name; }
    public void setGender(String gender) { this.gender = gender; }
    public void setAge(int age) { this.age = age; }
    public void setChineseScore(double chineseScore) { this.chineseScore = chineseScore; }
    public void setMathScore(double mathScore) { this.mathScore = mathScore; }
    public void setEnglishScore(double englishScore) { this.englishScore = englishScore; }

    // 计算总分和平均分方法
    public double getTotalScore() {
        return chineseScore + mathScore + englishScore;
    }

    public double getAverageScore() {
        return getTotalScore() / 3.0;
    }
}

接下来，我们创建一个名为`StudentTest`的测试类，用于创建和操作`Student`对象：

public class StudentTest {
    public static void main(String[] args) {
        // 创建一个Student对象
        Student student = new Student("张三", "男", 18, 95.0, 90.0, 88.0);

        // 赋值
        student.setName("李四");
        student.setAge(20);
        student.setMathScore(93.0);

        // 计算总分和平均分
        double totalScore = student.getTotalScore();
        double averageScore = student.getAverageScore();

        System.out.println("学生信息: " + student.getName());
        System.out.println("总分: " + totalScore);
        System.out.println("平均分: " + averageScore);
    }
}

在这个例子中，`StudentTest`的`main`方法创建了一个`Student`对象，并对学生的各项信息进行了设置，然后计算了总分和平均分，并将结果打印出来。