java 怎样 改变 数组元素的值

简介 （Introduction）：

背景 需要解析Object数组中的数据,将数据(mintime)进行修改,改为(maxtime),修改后,生成新的对象

结构图

核心 对于Object数组的概念理解,对于数组的解析理解,数组赋值的理解 详见:https://www.cnblogs.com/liuyangfirst/p/12364850.html

快速上手（Getting Started）

测试数据

1、创建测试对象

 class FunctionType {

     private String functionType;

     private Object[] objects;

     private boolean isDistinct;

     public String getFunctionType() {

         return functionType;

     }

     public void setFunctionType(String functionType) {

         this.functionType = functionType;

     }

     public Object[] getObjects() {

         return objects;

     }

     public void setObjects(Object[] objects) {

         this.objects = objects;

     }

     public boolean isDistinct() {

         return isDistinct;

     }

     public void setDistinct(boolean distinct) {

         isDistinct = distinct;

     }

     @Override

     protected Object clone() {

         FunctionType functionTypeDemo = new FunctionType();

         if (objects != null) {

             functionTypeDemo.setObjects(objects.clone());

         }

         functionTypeDemo.setFunctionType(functionType);

         functionTypeDemo.setDistinct(isDistinct);

         return functionTypeDemo;

     }

 }

2、创建测试数据

         FunctionType functionType = new FunctionType();

         functionType.setDistinct(false);

         functionType.setFunctionType("max");

         Object[] objects2 = new Object[1];

         objects2[0] = "mintime";

         functionType.setObjects(objects2);

         FunctionType functionType2 = new FunctionType();

         functionType2.setFunctionType("from_unixtime");

         functionType2.setDistinct(false);

         Object[] objects3 = new Object[2];

         objects3[0] = functionType;

         objects3[1] = "yyyy-MM-dd HH24:mi:ss";

         functionType2.setObjects(objects3);

3、创建修改方法

  private static void changeObjectParam(FunctionType functionType2, String string) {

         Object[] objects = functionType2.getObjects();

         // 替换

         Object[] replace = new Object[1];

         replace[0] = new String(string);

         for (int i = 0; i < objects.length; i++) {

             if (objects[0] instanceof FunctionType) {

                 FunctionType o = (FunctionType) objects[0];

                 if("max".equalsIgnoreCase(o.getFunctionType())){

                     if("mintime".equalsIgnoreCase(o.getObjects()[0].toString())){

                         o.setObjects(replace);

                     }

                 }

                 break;

             }

         }

         System.out.println(new Gson().toJson(functionType2));

     }

4、测试

 public static void main(String[] args) {

         FunctionType functionType = new FunctionType();

         functionType.setDistinct(false);

         functionType.setFunctionType("max");

         Object[] objects2 = new Object[1];

         objects2[0] = "mintime";

         functionType.setObjects(objects2);

         FunctionType functionType2 = new FunctionType();

         functionType2.setFunctionType("from_unixtime");

         functionType2.setDistinct(false);

         Object[] objects3 = new Object[2];

         objects3[0] = functionType;

         objects3[1] = "yyyy-MM-dd HH24:mi:ss";

         functionType2.setObjects(objects3);

         String string ="replace";

         // 修改mintime为maxtime

         // 修改mintime为maxtime

         changeObjectParam(functionType2, string);

     }

环境 JDK1.8

配置 IDEA编辑

存在问题 暂无

进阶篇 （Advanced）：
拓展object[]数据操作方法
1、根据传入的key，获取object中存的值
(1)方法

 /**

      * 获取object中存的值

      *

      * @param obj 传入的Object

      * @param key 传入的字段名称

      * @return 获取object中存的值

      */

     public static String getValueByKey(Object obj, String key) {

         // 得到类对象

         Class<?> objClass = obj.getClass();

         // 得到类中的所有属性集合

         Field[] fs = objClass.getDeclaredFields();

         for (Field f : fs) {

             // 设置些属性是可以访问的

             f.setAccessible(true);

             try {

                 if (f.getName().endsWith(key)) {

                     return f.get(obj).toString();

                 }

             } catch (IllegalArgumentException | IllegalAccessException e) {

                 e.printStackTrace();

             }

         }

         return "";

     }

(2)测试

 public static void main(String[] args) {

         Object[] objects = new Object[5];

         UserVO userVO = new UserVO("zhansan", "888");

         objects[0] = userVO;

         objects[1] = new Date();

         // name 是UserVO对象的字段属性名

         String name = getValueByKey(objects[0], "name");

         System.out.println("value: " + name);

 }

2、根据传入的值，获取object中存的key

(1)方法

 /**

      * 获取object中存的关键字

      *

      * @param obj 传入的Object

      * @return 获取object中存的关键字

      */

     public static String getKey(Object obj) {

         // 得到类对象

         Class<?> objClass = obj.getClass();

         // 得到类中的所有属性集合

         Field[] fs = objClass.getDeclaredFields();

         for (Field f : fs) {

             // 设置些属性是可以访问的

             f.setAccessible(true);

             try {

                 return f.getName();

             } catch (IllegalArgumentException e) {

                 e.printStackTrace();

             }

         }

         return "";

     }

(2)测试

 public static void main(String[] args) {

         Object[] objects = new Object[5];

         UserVO userVO = new UserVO("zhansan", "888");

         objects[0] = userVO;

         objects[1] = new Date();

         String key = getKey(objects[0]);

         System.out.println("key: " + key);

 }

3、根据传入的key，修改object[]中的对象的值

(1)方法

 /**

      * 修改object中参数的值

      *

      * @param obj      传入的Object

      * @param key      传入的字段名称

      * @param newValue 改变的值

      */

     public static void changeObjectValueByKey(Object obj, String key, String newValue) {

         // 得到类对象

         Class<?> objClass = obj.getClass();

         // 得到类中的所有属性集合

         Field[] fs = objClass.getDeclaredFields();

         for (Field f : fs) {

             // 设置些属性是可以访问的

             f.setAccessible(true);

             try {

                 if (f.getName().endsWith(key)) {

                     if (newValue.equalsIgnoreCase(f.get(obj).toString())) {

                         f.set(obj, key);

                     }

                 }

             } catch (IllegalArgumentException | IllegalAccessException e) {

                 e.printStackTrace();

             }

         }

     }

(2)测试

 public static void main(String[] args) {

         Object[] objects = new Object[5];

         UserVO userVO = new UserVO("zhansan", "888");

         objects[0] = userVO;

         objects[1] = new Date();

         changeObjectValueByKey(objects[0], "name", "lisi");

         System.out.println("user: " + new Gson().toJson(objects));

 }

4、根据传入的索引，修改object[]中的对象的值

(1)方法

 public static void changeObjectValue(Object[] obj, int index, String newValue) {

         for (int i = 0; i < obj.length; i++) {

             if (i == index) {

                 if (obj[i] instanceof Object[]) {

                     Object[] objects = (Object[]) obj[i];

                     objects[0] = newValue;

                 }

             }

         }

     }

(2)测试

 public static void main(String[] args) {

         Object[] objects = new Object[5];

         UserVO userVO = new UserVO("zhansan", "888");

         objects[0] = userVO;

         objects[1] = new Date();

         changeObjectValue(objects, 0, "lisi");

         System.out.println("user: " + new Gson().toJson(objects));

 }

5、修改object中的值

(1)方法

 public static String getChildValueFromList(Object[] obj, int index) {

         for (int i = 0; i < obj.length; i++) {

             if (i == index) {

                 if (obj[i] instanceof Object[]) {

                     Object[] objects = (Object[]) obj[i];

                     return objects[0].toString();

                 }

             }

         }

         return "";

     }

(2)测试

 public static void main(String[] args) {

         Object[] objects = new Object[5];

         UserVO userVO = new UserVO("zhansan", "888");

         objects[0] = userVO;

         objects[1] = new Date();

         String childValue = getChildValueFromList(objects, 2);

         System.out.println("childValue: " + childValue);

 }

java 怎样 改变 数组元素的值的相关教程结束。