java中每次for循环都生成一个新的Map<String, Object> condition1 = new HashMap<>();将其存放到list中 map的名称不能重复

在Java中，如果你想要在每次for循环中创建一个新的`Map<String, Object>`实例，并将这个新地图放入一个列表中，你可以这样做：

List<Map<String, Object>> conditionMaps = new ArrayList<>();
for (int i = 0; i < someCondition; i++) { // 假设someCondition是你需要迭代的次数
    Map<String, Object> condition1 = new HashMap<>(); // 每次循环都会创建一个新的Map对象
    // 对condition1添加你需要的数据
    condition1.put("key1", value1);
    condition1.put("key2", value2);
    // 将新的条件地图添加到列表中
    conditionMaps.add(condition1);
}

在这个例子中，`conditionMaps`是一个存储了多个`HashMap<String, Object>`的列表，它们都是在for循环的不同迭代过程中独立创建的。

相关问题

java中每次for循环都生成一个新的Map<String, Object> condition1 = new HashMap<>(); map的名称不能重复

在Java中，如果你需要在每次for循环中创建新的`Map<String, Object>`实例，确实可以这样做，因为`Map`是引用类型，所以每次分配的是一个新的内存地址。例如：

for (int i = 0; i < someList.size(); i++) {
    Map<String, Object> condition1 = new HashMap<>(); // 创建一个新的HashMap实例
    // 这里的condition1是一个独立的变量，与其他循环迭代无关
    condition1.put("key", "value"); // 对每个新地图添加元素
}

然而，如果目的是为了在循环外部能够访问到这些单独的`Map`实例，你可以考虑将它们存储在一个列表或数组中，比如：

List<Map<String, Object>> conditions = new ArrayList<>();
for (int i = 0; i < someList.size(); i++) {
    conditions.add(new HashMap<>());
    conditions.get(i).put("key", "value");
}

// 现在你可以通过索引来访问每个条件
conditions.get(0); // 获取第一个条件

在这种情况下，`conditions`列表会保存每次循环创建的新`Map`。

mybatisPlus Map<String, String>

MyBatis Plus is an enhanced version of the MyBatis framework, which is a popular persistence framework for Java. It simplifies the usage of MyBatis and provides additional features.

In MyBatis Plus, you can use the `Map<String, String>` type to represent key-value pairs. This can be useful in scenarios where you want to pass dynamic parameters to a SQL query or store dynamic properties in a database column.

Here's an example of how you can use `Map<String, String>` with MyBatis Plus:

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.service.additional.query.impl.QueryChainWrapper;

import java.util.HashMap;
import java.util.Map;

public class MyBatisPlusExample {
    public static void main(String[] args) {
        // Create a map with key-value pairs
        Map<String, String> params = new HashMap<>();
        params.put("name", "John");
        params.put("age", "30");

        // Create a query wrapper
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();

        // Add conditions using the map
        params.forEach((key, value) -> queryWrapper.eq(key, value));

        // Execute the query
        UserMapper userMapper = new UserMapper();
        List<User> userList = userMapper.selectList(queryWrapper);
    }
}

In this example, we create a `Map<String, String>` called `params`, which contains key-value pairs representing the conditions we want to add to the query. We then iterate over the map using `forEach` and add each condition to the `QueryWrapper` using the `eq` method. Finally, we execute the query and retrieve the results.

Note that this is just a basic example, and you can use `Map<String, Object>` if you need to handle values of different types. MyBatis Plus provides many other features and utilities that can simplify your database operations.