从ArrayList检索特定数据的Java
我在Java程序中有一个ArrayList,该程序使用下面的类填充从ArrayList检索特定数据的Java,java,class,arraylist,printing,Java,Class,Arraylist,Printing,我在Java程序中有一个ArrayList,该程序使用下面的类填充 public class Mayhem { public static void main(String[] args) { int lv_cnt; int lv_num01; int lv_num02; List<User> userList = new ArrayList<>(); lv_cnt = 0;
public class Mayhem {
public static void main(String[] args) {
int lv_cnt;
int lv_num01;
int lv_num02;
List<User> userList = new ArrayList<>();
lv_cnt = 0;
lv_num01 = 0;
lv_num02 = 0;
while(lv_cnt != 3) {
lv_num01 = lv_num01 + 1;
lv_num02 = lv_num02 + 5;
userList.add(new User(lv_num01, lv_num02));
lv_cnt = lv_cnt + 1;
}
// how do I retrieve data from the second userList.add?
}
}
class User {
private int idno;
private int rela;
public User(int idno, int rela) {
this.idno = idno;
this.rela = rela;
}
}
公共级混乱{
公共静态void main(字符串[]args){
国际物流中心;
int lv_num01;
int lv_num02;
List userList=new ArrayList();
lv_cnt=0;
lv_num01=0;
lv_num02=0;
而(lv_cnt!=3){
lv_num01=lv_num01+1;
lv_num02=lv_num02+5;
添加(新用户(lv_num01,lv_num02));
lv_cnt=lv_cnt+1;
}
//如何从第二个userList.add中检索数据?
}
}
类用户{
私人国际电话号码;
私人内部关系;
公共用户(int idno、int rela){
this.idno=idno;
this.rela=rela;
}
}
这一切都很好,但是如何打印第二次循环时的数据呢?(例如)。第二个可通过以下方式检索:
System.out.println(userList.get(1.getIdno())代码>
这里是完整的代码。您必须向用户类添加一些公共方法来检索值
public static void main(String[] args) {
int lv_cnt;
int lv_num01;
int lv_num02;
List<User> userList = new ArrayList<User>();
lv_cnt = 0;
lv_num01 = 0;
lv_num02 = 0;
while (lv_cnt != 3) {
lv_num01 = lv_num01 + 1;
lv_num02 = lv_num02 + 5;
userList.add(new User(lv_num01, lv_num02));
lv_cnt = lv_cnt + 1;
}
System.out.println(userList.get(0).getIdno());
System.out.println(userList.get(1).getIdno());
System.out.println(userList.get(2).getIdno());
// how do I retrieve data from the second userList.add?
}
}
class User {
private int idno;
private int rela;
public User(int idno, int rela) {
this.idno = idno;
this.rela = rela;
}
public int getIdno() {
return idno;
}
}
publicstaticvoidmain(字符串[]args){
国际物流中心;
int lv_num01;
int lv_num02;
List userList=new ArrayList();
lv_cnt=0;
lv_num01=0;
lv_num02=0;
而(lv_cnt!=3){
lv_num01=lv_num01+1;
lv_num02=lv_num02+5;
添加(新用户(lv_num01,lv_num02));
lv_cnt=lv_cnt+1;
}
System.out.println(userList.get(0.getIdno());
System.out.println(userList.get(1.getIdno());
System.out.println(userList.get(2.getIdno());
//如何从第二个userList.add中检索数据?
}
}
类用户{
私人国际电话号码;
私人内部关系;
公共用户(int idno、int rela){
this.idno=idno;
this.rela=rela;
}
public int getIdno(){
返回idno;
}
}
这非常有效,非常感谢edubri。。。谢谢你,男士:D