demo(class40): 函数式变成（静态方法引用、实例方法引用、特定类型方法引用）

- 新增 Demo1、Demo2、Demo3 和 Student 类
- 示例代码展示了使用静态方法引用、实例方法引用和 Lambda 表达式进行排序
- 包含按年龄和身高排序学生对象的逻辑
- 添加了字符串数组的排序示例

src/class40/Demo1.java

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+package class40;
+
+import java.util.Arrays;
+
+public class Demo1 {
+    public static void main(String[] args) {
+        Student[] students = new Student[6];
+        students[0] = new Student("般素素", 35, 171.5, '女');
+        students[1] = new Student("杨幂", 28, 168.5, '女');
+        students[2] = new Student("张无忌", 25, 181.5, '男');
+        students[3] = new Student("小昭", 19, 165.5, '女');
+        students[4] = new Student("赵敏", 27, 167.5, '女');
+        students[5] = new Student("刘亦菲", 36, 168, '女');
+
+//        Arrays.sort(students,(o1, o2)-> o1.getAge()-o2.getAge());
+//
+//        Arrays.sort(students , ((o1, o2) -> Student.compareByAge(o1, o2)));
+
+        Arrays.sort(students, Student::compareByAge);//静态方法引用，简化lambda表达式
+    }
+}

src/class40/Demo2.java

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+package class40;
+
+import java.util.Arrays;
+
+public class Demo2 {
+    public static void main(String[] args) {
+        Student[] students = new Student[6];
+        students[0] = new Student("般素素", 35, 171.5, '女');
+        students[1] = new Student("杨幂", 28, 168.5, '女');
+        students[2] = new Student("张无忌", 25, 181.5, '男');
+        students[3] = new Student("小昭", 19, 165.5, '女');
+        students[4] = new Student("赵敏", 27, 167.5, '女');
+        students[5] = new Student("刘亦菲", 36, 168, '女');
+
+
+        Student t = new Student();
+        Arrays.sort(students, Student::compareByAge);
+//        Arrays.sort(students, ((o1, o2) -> t.compareByHeight(o1, o2)));
+        Arrays.sort(students, (t::compareByHeight)); //实例方法引用
+
+    }
+
+}

src/class40/Demo3.java

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+package class40;
+
+import java.util.Arrays;
+import java.util.Comparator;
+
+public class Demo3 {
+    public static void main(String[] args) {
+        //创建一个字符串数组，用来模拟一个手机通讯录（英文名）
+        String[] names = {"Tom","Jerry","Bobi","曹操","Mike","angela","Dlei","Mary","Rose","Andy","caocao"};
+//      方法1
+        Arrays.sort(names, new Comparator<String>() {
+            @Override
+            public int compare(String o1, String o2) {
+                return o1.compareToIgnoreCase(o2);
+            }
+        }); //默认首字母排序，大写在前，小写字母在后，中文最后
+
+//      方法2
+        Arrays.sort(names, (o1, o2) -> o1.compareToIgnoreCase(o2));
+
+
+//      方法3
+        Arrays.sort(names, String::compareToIgnoreCase);
+
+
+
+
+        System.out.println(Arrays.toString(names));
+
+
+
+    }
+}

src/class40/Student.java

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+package class40;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+
+public class Student {
+    private String name;
+    private int age;
+    private double height;
+    private char sex;
+    public static int compareByAge(Student o1, Student o2){
+        return o1.getAge() - o2.getAge();
+    }
+    public int compareByHeight(Student o1, Student o2){
+        return Double.compare(o1.getHeight(), o2.getHeight());
+    }
+}