Java 如何将数据库中的值存储到集合中?
}Java 如何将数据库中的值存储到集合中?,java,collections,Java,Collections,} 所以我有这部分代码,我正在从mysql数据库中阅读它,我想知道如何将对象存储到集合中(名称和年龄)?首先,创建一个带有“Name”和“age”字段的Person类。还添加相应的getter和setter 然后修改您的代码,如下所示: public String getDataOfpersons() { try { String query = "select * from persons"; rs = st.executeQuery(query)
所以我有这部分代码,我正在从mysql数据库中阅读它,我想知道如何将对象存储到集合中(名称和年龄)?首先,创建一个带有“Name”和“age”字段的Person类。还添加相应的getter和setter 然后修改您的代码,如下所示:
public String getDataOfpersons() {
try {
String query = "select * from persons";
rs = st.executeQuery(query);
System.out.println("Records from persons database");
while(rs.next()) {
String name = rs.getString("name");
String age = rs.getString("age");
System.out.println("Name: " + name + " " + "age: " + age);
}
}catch(Exception ex) {
System.out.println(ex);
}
return null;
//更改返回类型
公共列表getDataOfpersons(){
//创建一个列表来存储值
List personList=新建ArrayList();
试一试{
String query=“从人员中选择*”;
rs=st.executeQuery(查询);
System.out.println(“来自个人数据库的记录”);
while(rs.next()){
Person=新人();
字符串名称=rs.getString(“名称”);
字符串年龄=rs.getString(“年龄”);
person.setName(name);
人.体位(年龄);
personList.add(person);
System.out.println(“名称:“+Name+”+“+”年龄:“+age”);
}
}捕获(例外情况除外){
系统输出打印项次(ex);
}
回归人格;
}
在不更改现有方法签名的情况下,不知道这是否是您想要的
// change the return type
public List<Person> getDataOfpersons() {
// create a list to store values
List<Person> personList = new ArrayList<>();
try {
String query = "select * from persons";
rs = st.executeQuery(query);
System.out.println("Records from persons database");
while (rs.next()) {
Person person = new Person();
String name = rs.getString("name");
String age = rs.getString("age");
person.setName(name);
person.setAge(age);
personList.add(person);
System.out.println("Name: " + name + " " + "age: " + age);
}
} catch(Exception ex) {
System.out.println(ex);
}
return personList;
}
公共字符串getDataOfpersons(){
试一试{
Map Map=newhashmap();
String query=“从人员中选择*”;
rs=st.executeQuery(查询);
System.out.println(“来自个人数据库的记录”);
while(rs.next()){
字符串名称=rs.getString(“名称”);
字符串年龄=rs.getString(“年龄”);
//System.out.println(“名称:“+Name+”+“+”年龄:“+age”);
地图。放置(“名称”,名称);
地图放置(“年龄”,年龄);
系统输出打印项次(map);
}
}捕获(例外情况除外){
系统输出打印项次(ex);
}
返回null;
}
您是说您不知道如何使用SQL和JDBC接口将数据插入数据库?
public String getDataOfpersons() {
try {
Map<String,String> map = new HashMap<>();
String query = "select * from persons";
rs = st.executeQuery(query);
System.out.println("Records from persons database");
while(rs.next()) {
String name = rs.getString("name");
String age = rs.getString("age");
//System.out.println("Name: " + name + " " + "age: " + age);
map.put("Name",name);
map.put("age",age);
System.out.println(map);
}
}catch(Exception ex) {
System.out.println(ex);
}
return null;
}