update codes and docs

README.md

@@ -30,7 +30,7 @@
 - [Java 基础语法特性](docs/basics/java-basic-grammar.md)
 - [Java 基本数据类型](docs/basics/java-data-type.md)
 - [Java String 类型](docs/basics/java-string.md)
-- [Java 类和对象](docs/basics/java-class.md)
+- [Java 面向对象](docs/basics/java-oop.md)
 - [Java 方法](docs/basics/java-method.md)
 - [Java 数组](docs/basics/java-array.md)
 - [Java 枚举](docs/basics/java-enum.md)

codes/javacore-basics/pom.xml

@@ -16,9 +16,9 @@
   <name>JavaCore :: Basics</name>
 
   <properties>
-    <java.version>1.7</java.version>
+    <java.version>1.8</java.version>
     <maven.compiler.source>${java.version}</maven.compiler.source>
     <maven.compiler.target>${java.version}</maven.compiler.target>
   </properties>
-  
+
 </project>

codes/javacore-basics/src/main/java/io/github/dunwu/javacore/datatype/Integer判等.java

@@ -0,0 +1,35 @@
+package io.github.dunwu.javacore.datatype;
+
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * @author <a href="mailto:[email protected]">Zhang Peng</a>
+ * @since 2020-08-06
+ */
+@Slf4j
+public class Integer判等 {
+
+    public static void main(String[] args) {
+        Integer a = 127; //Integer.valueOf(127)
+        Integer b = 127; //Integer.valueOf(127)
+        log.info("\nInteger a = 127;\nInteger b = 127;\na == b ? {}", a == b);    // true
+
+        Integer c = 128; //Integer.valueOf(128)
+        Integer d = 128; //Integer.valueOf(128)
+        log.info("\nInteger c = 128;\nInteger d = 128;\nc == d ? {}", c == d);   //false
+        //设置-XX:AutoBoxCacheMax=1000再试试
+
+        Integer e = 127; //Integer.valueOf(127)
+        Integer f = new Integer(127); //new instance
+        log.info("\nInteger e = 127;\nInteger f = new Integer(127);\ne == f ? {}", e == f);   //false
+
+        Integer g = new Integer(127); //new instance
+        Integer h = new Integer(127); //new instance
+        log.info("\nInteger g = new Integer(127);\nInteger h = new Integer(127);\ng == h ? {}", g == h);  //false
+
+        Integer i = 128; //unbox
+        int j = 128;
+        log.info("\nInteger i = 128;\nint j = 128;\ni == j ? {}", i == j); //true
+    }
+
+}

codes/javacore-basics/src/main/java/io/github/dunwu/javacore/datatype/Lombok生成Equals的问题.java

@@ -0,0 +1,58 @@
+package io.github.dunwu.javacore.datatype;
+
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * @author <a href="mailto:[email protected]">Zhang Peng</a>
+ * @since 2020-08-06
+ */
+@Slf4j
+public class Lombok生成Equals的问题 {
+
+    public static void main(String[] args) {
+        test1();
+        test2();
+    }
+
+    public static void test1() {
+        Person person1 = new Person("zhuye", "001");
+        Person person2 = new Person("Joseph", "001");
+        log.info("person1.equals(person2) ? {}", person1.equals(person2));
+    }
+
+    public static void test2() {
+        Employee employee1 = new Employee("zhuye", "001", "bkjk.com");
+        Employee employee2 = new Employee("Joseph", "002", "bkjk.com");
+        log.info("employee1.equals(employee2) ? {}", employee1.equals(employee2));
+    }
+
+    @Data
+    static class Person {
+
+        @EqualsAndHashCode.Exclude
+        private String name;
+        private String identity;
+
+        public Person(String name, String identity) {
+            this.name = name;
+            this.identity = identity;
+        }
+
+    }
+
+    @Data
+    @EqualsAndHashCode(callSuper = true)
+    static class Employee extends Person {
+
+        private String company;
+
+        public Employee(String name, String identity, String company) {
+            super(name, identity);
+            this.company = company;
+        }
+
+    }
+
+}

codes/javacore-basics/src/main/java/io/github/dunwu/javacore/datatype/StringIntern性能测试.java

@@ -0,0 +1,28 @@
+package io.github.dunwu.javacore.datatype;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+/**
+ * 没事别轻易用 {@link String#intern}，如果要用一定要注意控制驻留的字符串的数量，并留意常量表的各项指标
+ *
+ * @author <a href="mailto:[email protected]">Zhang Peng</a>
+ * @since 2020-08-06
+ */
+public class StringIntern性能测试 {
+
+    public static void main(String[] args) {
+        //-XX:+PrintStringTableStatistics，可以打印出字符串常量表的统计信息
+        //设置 -XX:StringTableSize=10000000 后，执行速度会快很多
+        List<String> list = new ArrayList<>();
+        long begin = System.currentTimeMillis();
+        list = IntStream.rangeClosed(1, 10000000)
+            .mapToObj(i -> String.valueOf(i).intern())
+            .collect(Collectors.toList());
+        System.out.println("size:" + list.size());
+        System.out.println("time:" + (System.currentTimeMillis() - begin));
+    }
+
+}

codes/javacore-basics/src/main/java/io/github/dunwu/javacore/datatype/String判等.java

@@ -0,0 +1,30 @@
+package io.github.dunwu.javacore.datatype;
+
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * @author <a href="mailto:[email protected]">Zhang Peng</a>
+ * @since 2020-08-06
+ */
+@Slf4j
+public class String判等 {
+
+    public static void main(String[] args) {
+        String a = "1";
+        String b = "1";
+        log.info("\nString a = \"1\";\nString b = \"1\";\na == b ? {}", a == b); //true
+
+        String c = new String("2");
+        String d = new String("2");
+        log.info("\nString c = new String(\"2\");\nString d = new String(\"2\");\nc == d ? {}", c == d); //false
+
+        String e = new String("3").intern();
+        String f = new String("3").intern();
+        log.info("\nString e = new String(\"3\").intern();\nString f = new String(\"3\").intern();\ne == f ? {}", e == f); //true
+
+        String g = new String("4");
+        String h = new String("4");
+        log.info("\nString g = new String(\"4\");\nString h = new String(\"4\");\ng == h ? {}", g.equals(h)); //true
+    }
+
+}

codes/javacore-basics/src/main/java/io/github/dunwu/javacore/datatype/equals和CompareTo.java

@@ -0,0 +1,90 @@
+package io.github.dunwu.javacore.datatype;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.extern.slf4j.Slf4j;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * @author <a href="mailto:[email protected]">Zhang Peng</a>
+ * @since 2020-08-06
+ */
+@Slf4j
+public class equals和CompareTo {
+
+    public static void main(String[] args) {
+        wrong();
+        right();
+    }
+
+    public static void wrong() {
+
+        List<Student> list = new ArrayList<>();
+        list.add(new Student(1, "zhang"));
+        list.add(new Student(2, "wang"));
+        Student student = new Student(2, "li");
+
+        log.info("ArrayList.indexOf");
+        int index1 = list.indexOf(student);
+        Collections.sort(list);
+        log.info("Collections.binarySearch");
+        int index2 = Collections.binarySearch(list, student);
+
+        log.info("index1 = " + index1);
+        log.info("index2 = " + index2);
+    }
+
+    public static void right() {
+
+        List<StudentRight> list = new ArrayList<>();
+        list.add(new StudentRight(1, "zhang"));
+        list.add(new StudentRight(2, "wang"));
+        StudentRight student = new StudentRight(2, "li");
+
+        log.info("ArrayList.indexOf");
+        int index1 = list.indexOf(student);
+        Collections.sort(list);
+        log.info("Collections.binarySearch");
+        int index2 = Collections.binarySearch(list, student);
+
+        log.info("index1 = " + index1);
+        log.info("index2 = " + index2);
+    }
+
+    @Data
+    @AllArgsConstructor
+    static class Student implements Comparable<Student> {
+
+        private int id;
+        private String name;
+
+        @Override
+        public int compareTo(Student other) {
+            int result = Integer.compare(other.id, id);
+            if (result == 0) { log.info("this {} == other {}", this, other); }
+            return result;
+        }
+
+    }
+
+    @Data
+    @AllArgsConstructor
+    static class StudentRight implements Comparable<StudentRight> {
+
+        private int id;
+        private String name;
+
+        @Override
+        public int compareTo(StudentRight other) {
+            return Comparator.comparing(StudentRight::getName)
+                .thenComparingInt(StudentRight::getId)
+                .compare(this, other);
+        }
+
+    }
+
+}

codes/javacore-basics/src/main/java/io/github/dunwu/javacore/datatype/DataTypeDemo01.java → codes/javacore-basics/src/main/java/io/github/dunwu/javacore/datatype/值类型使用示例.java

@@ -7,7 +7,7 @@
  * @author <a href="mailto:[email protected]">Zhang Peng</a>
  * @since 2019-03-26
  */
-public class DataTypeDemo01 {
+public class 值类型使用示例 {
 
     public static void demo1() {
         // compile error
@@ -95,7 +95,7 @@ public static void demo9() {
     public static void main(String[] args)
         throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
         for (int i = 1; i <= 10; i++) {
-            Method method = DataTypeDemo01.class.getMethod("demo" + i);
+            Method method = 值类型使用示例.class.getMethod("demo" + i);
             method.invoke(null);
         }
     }

codes/javacore-basics/src/main/java/io/github/dunwu/javacore/datatype/DataTypeDemo02.java → codes/javacore-basics/src/main/java/io/github/dunwu/javacore/datatype/包装类型使用示例.java

@@ -4,7 +4,7 @@
  * @author <a href="mailto:[email protected]">Zhang Peng</a>
  * @since 2019-03-26
  */
-public class DataTypeDemo02 {
+public class 包装类型使用示例 {
 
     public static void main(String[] args) {
         printByte();

codes/javacore-basics/src/main/java/io/github/dunwu/javacore/datatype/BoxingDemo.java → codes/javacore-basics/src/main/java/io/github/dunwu/javacore/datatype/包装类装箱拆箱.java

@@ -6,7 +6,7 @@
  * @author <a href="mailto:[email protected]">Zhang Peng</a>
  * @since 2019-03-10
  */
-public class BoxingDemo {
+public class 包装类装箱拆箱 {
 
     public static void main(String[] args) {
         Integer i1 = 10; // 自动装箱

codes/javacore-basics/src/main/java/io/github/dunwu/javacore/datatype/枚举判等.java

@@ -0,0 +1,45 @@
+package io.github.dunwu.javacore.datatype;
+
+import lombok.Data;
+
+/**
+ * @author <a href="mailto:[email protected]">Zhang Peng</a>
+ * @since 2020-08-06
+ */
+public class 枚举判等 {
+
+    public static void main(String[] args) {
+        StatusEnum statusEnum = StatusEnum.DELIVERED;
+        OrderQuery orderQuery = new OrderQuery(StatusEnum.DELIVERED.status, StatusEnum.DELIVERED.desc);
+        System.out.println(statusEnum.status == orderQuery.getStatus());
+    }
+
+    @Data
+    static class OrderQuery {
+
+        private Integer status;
+        private String name;
+
+        public OrderQuery(Integer status, String name) {
+            this.status = status;
+            this.name = name;
+        }
+
+    }
+
+    enum StatusEnum {
+        CREATED(1000, "已创建"),
+        PAID(1001, "已支付"),
+        DELIVERED(1002, "已送到"),
+        FINISHED(1003, "已完成");
+
+        private final Integer status;
+        private final String desc;
+
+        StatusEnum(Integer status, String desc) {
+            this.status = status;
+            this.desc = desc;
+        }
+    }
+
+}