用ArrayList实现用户信息的添加，删除，更新，查询

package jpack; import java.util.*; import java.io.*; public class Usermanage { ArrayList a = new ArrayList(); User u= new User(); boolean singal=true; public void addUser()throws IOException { System.out.print("输入要添加的ID:"); BufferedReader In=new BufferedReader(new InputStreamReader(System.in)); String Id=In.readLine(); System.out.print("输入要添加的Name:"); String Name=In.readLine(); System.out.print("输入要添加的Password:"); String Pass=In.readLine(); User u = new User(Id,Name, Pass); a.add(u); } public void display() { Iterator i=a.iterator(); while(i.hasNext()){ User u=(User)(i.next());//把它转换为自己的对象 System.out.println("序列表的内容为： "+"ID: "+u.ID +" "+"name: "+u.name+" "+ "password: "+ u.password); } } public void delete(List<User>a,String c,String b) { for(int i=0;i<a.size();i++) { User p=(User)a.get(i); if(c.equals("a")) { if(p.getName().equals(b)) a.remove(p); } if( c.equals("b")) { if(p.getId().equals(b)) a.remove(i); } } } public void del()throws IOException { System.out.print("输入要删除的ID:"); BufferedReader In=new BufferedReader(new InputStreamReader(System.in)); String Id=In.readLine(); for(int i=0;i<a.size();i++) { User p=(User)a.get(i); if(p.getId().equals(Id)) { System.out.println("此ID号对应的信息为："+"ID:　 " +p.getId()+" "+ "name: "+ p.getName()+" "+ "password "+p.getPassword() ); System.out.println("确认是否删除此记录，是输入Y,否则输入N:"); String Iden=In.readLine(); { if(Iden.equals("Y")) a.remove(i); //else // break; } singal=false; } } if(singal) System.out.println("无你要删除的ID信息！"); } public void Update()throws IOException { System.out.print("输入要更新的ID:"); BufferedReader In=new BufferedReader(new InputStreamReader(System.in)); String Id=In.readLine(); for(int i=0;i<a.size();i++) { User p=(User)a.get(i); if(p.getId().equals(Id)) { System.out.print("输入要更新后的ID:"); String id=In.readLine(); p.ID= id; System.out.print("输入要添加的Name:"); String Name=In.readLine(); p.name = Name; System.out.print("输入要添加的Password:"); String Pass=In.readLine(); p.password = Pass; singal=false; } } if(singal) System.out.println("无你要找更新的ID信息！"); } public void searchById()throws IOException { System.out.print("输入要查询的ID:"); BufferedReader In=new BufferedReader(new InputStreamReader(System.in)); String Id=In.readLine(); boolean singal=true; for(int i=0;i<a.size();i++) { User p=(User)a.get(i); if(p.getId().equals(Id)) { System.out.println("此ID对应的信息为："+"ID: "+p.getId()+" "+ "name: "+ p.getName()+" "+ "password: "+p.getPassword() ); singal=false; } } if(singal) System.out.println("无你要找的ID信息！"); else return; } public void searchByNameExact()throws IOException { System.out.print("输入要查询的Name:"); BufferedReader In=new BufferedReader(new InputStreamReader(System.in)); String Name=In.readLine(); for(int i=0;i<a.size();i++) { User p=(User)a.get(i); if(p.getName().equals(Name)) { System.out.println("此Name对应的信息为："+"ID: "+p.getId()+" "+ "name: "+ p.getName()+" "+ "password: "+p.getPassword() ); singal=false; } } if(singal) System.out.println("无你要找的Name信息！"); } public void searchByNameSimple()throws IOException { System.out.print("输入要查询的Name:"); BufferedReader In=new BufferedReader(new InputStreamReader(System.in)); String Name=In.readLine(); for(int i=0;i<a.size();i++) { User p=(User)a.get(i); if(p.getName().contains(Name)) { System.out.println("此Name对应的信息为："+"ID: "+p.getId()+" "+ "name: "+ p.getName()+" "+ "password: "+p.getPassword() ); singal=false; } } if(singal) System.out.println("无你要查询的Name的信息！"); } }