补充下面代码,怎么使程序一直执行,就是用户名,密码错了还可以再输入:package com.tarena.day03;import java.util.Scanner;public class a {
public static void main(String[] args){
int sysqq=888888,qq=0,sysmm=666666,mm=0;
System.out.println("请输入QQ号码与密码");
Scanner s=new Scanner(System.in);
qq=s.nextInt();
Scanner s1=new Scanner(System.in);
mm=s1.nextInt();
if(qq!=0&&mm!=0){
System.out.println("系统登录中");
if(sysqq==qq&&sysmm!=mm){
System.out.println(" 密码错误");
return;
}else{
if(sysqq==qq&&sysmm==mm){
System.out.println("登录成功");
}else{
System.out.println("账号错误");
}
}
}else{
System.out.println("请输入QQ账号");
}
}
}
public static void main(String[] args){
int sysqq=888888,qq=0,sysmm=666666,mm=0;
System.out.println("请输入QQ号码与密码");
Scanner s=new Scanner(System.in);
qq=s.nextInt();
Scanner s1=new Scanner(System.in);
mm=s1.nextInt();
if(qq!=0&&mm!=0){
System.out.println("系统登录中");
if(sysqq==qq&&sysmm!=mm){
System.out.println(" 密码错误");
return;
}else{
if(sysqq==qq&&sysmm==mm){
System.out.println("登录成功");
}else{
System.out.println("账号错误");
}
}
}else{
System.out.println("请输入QQ账号");
}
}
}
public static void main(String[] args) {
int sysqq=888888,qq=0,sysmm=666666,mm=0;
Scanner s=new Scanner(System.in);
System.out.println("请输入QQ号码与密码");
while(true)
{
qq=s.nextInt();
mm=s.nextInt();
if(qq!=sysqq&&mm!=sysmm)
{
System.out.println("请重新输入账号密码");
}
else
System.out.println("成功登陆");
break;
}
}
import java.util.Scanner;
public class QQ{
public static void main(String[] args) {
int sysqq=888888,sysmm=666666;
System.out.println("请输入QQ号码与密码");
invalidate(sysqq,sysmm);
}
public static void invalidate(int sysqq,int sysmm){
int qq=0,mm=0;
Scanner s=new Scanner(System.in);
qq=s.nextInt();
mm=s.nextInt();
if(qq==sysqq&&mm==sysmm){
System.out.println("成功登陆");
}else{
System.out.println("请重新输入账号密码");
invalidate(sysqq,sysmm);
}
}
}只是如题简单的判断,当然对你输入还需要异常处理。
public static void main(String[] args) {
int sysqq = 888888, qq = 0, sysmm = 666666, mm = 0;
Scanner s = new Scanner(System.in);
System.out.println("请输入QQ号码与密码");
while (true) {
qq = s.nextInt();
mm = s.nextInt();
if (qq != sysqq && mm != sysmm) {
System.out.println("请重新输入账号密码");
} else{
System.out.println("成功登陆");
break;
}
}
}
public static void main(String[] args) {
int sysqq = 888888, qq = 0, sysmm = 666666, mm = 0;
boolean flag = true;
while(flag){
System.out.println("请输入QQ号码与密码");
Scanner s = new Scanner(System.in);
qq = s.nextInt();
Scanner s1 = new Scanner(System.in);
mm = s1.nextInt();
if (qq != 0 && mm != 0) {
System.out.println("系统登录中");
if (sysqq == qq && sysmm != mm) {
System.out.println(" 密码错误");
return;
} else {
if (sysqq == qq && sysmm == mm) {
System.out.println("登录成功");
flag = false;
} else {
System.out.println("账号错误");
} }
} }
public static void main(String[] args) {
int sysqq = 888888, qq = 0, sysmm = 666666, mm = 0;
boolean flag = true;
while(flag){
System.out.println("请输入QQ号码与密码");
Scanner s = new Scanner(System.in);
qq = s.nextInt();
Scanner s1 = new Scanner(System.in);
mm = s1.nextInt();
if (qq != 0 && mm != 0) {
System.out.println("系统登录中");
if (sysqq == qq && sysmm != mm) {
System.out.println(" 密码错误");
return;
} else {
if (sysqq == qq && sysmm == mm) {
System.out.println("登录成功");
flag = false;
} else {
System.out.println("账号错误");
} }
} }
{
int sysqq = 888888, qq = 0, sysmm = 666666, mm = 0;
Scanner s = new Scanner(System.in);
System.out.println("请输入QQ号码与密码");
while (true) {
qq = s.nextInt();
mm = s.nextInt();
if (qq != sysqq && mm != sysmm) {
System.out.println("请重新输入账号密码");
} else{
System.out.println("成功登陆");
break;
}
}
}判断条件错了,应该是:if(!(qq==sysqq && mm==sysmm))