为什么不能输出想要的结果

Question

package in;import java.util.Scanner;public class SellGoodsSystem {
static String[] goodsArray;
public void goodsDisplay(){
 goodsArray=new String[]{"0:醒目","1:鲜橙多","2:潘石榴","3:娃哈哈" ,
"4:绿茶","5:红茶","6:可口可乐"};
System.out.print("商品");
for(int i=0;i<goodsArray.length;i++){
System.out.print("    "+goodsArray[i]);
}
}
public static void main(String[] args) {
SellGoodsSystem goods=new SellGoodsSystem();
goods.goodsDisplay();
System.out.print("\n");
Scanner scanner=new Scanner(System.in);
System.out.println("请输入你想要饮料的序号：");
if(scanner.hasNextInt()){
int a=scanner.nextInt();
if((a<0)&&(a>6)){
System.out.println(goodsArray[a]);
}else{
System.out.print("警告！！你的操作不正确！"); 
}
}
else{
System.out.println("您的操作不正确！");
}
}
}

Answer 1

ｉｆ／ｅｌｓｅ你写反了．if ((a < 0) && (a > 6)) {
                System.out.print("警告！！你的操作不正确！");
            } else {
                System.out.println(goodsArray[a]);
            }

Answer 2

建议把
goodsArray=new String[]{"0:醒目","1:鲜橙多","2:潘石榴","3:娃哈哈" ,
"4:绿茶","5:红茶","6:可口可乐"}; 
放到构造方法里．

Answer 3

import java.util.Scanner;public class SellGoodsSystem { static String[] goodsArray; public void goodsDisplay() {
goodsArray = new String[] { "0:醒目", "1:鲜橙多", "2:潘石榴", "3:娃哈哈", "4:绿茶",
"5:红茶", "6:可口可乐" };
System.out.print("商品");
for (int i = 0; i < goodsArray.length; i++) {
System.out.print("    " + goodsArray[i]);
}
} public static void main(String[] args) {
SellGoodsSystem goods = new SellGoodsSystem();
goods.goodsDisplay();
System.out.print("\n");
Scanner scanner = new Scanner(System.in);
System.out.println("请输入你想要饮料的序号：");
if (scanner.hasNextInt()) {
int a = scanner.nextInt();
//这里判断写反了吧，太粗心了
if ((a >= 0) && (a <= 6)) {
System.out.println(goodsArray[a]);
} else {
System.out.print("警告！！你的操作不正确！");
}
} else {
System.out.println("您的操作不正确！");
}
}
}楼主要细心啊！

Answer 4

判断条件不对，应该是0<a<6的时候输出啊！

Answer 5

楼主，你想输出什么？
goods.goodsDisplay(); 执行的时候应该输出：
商品    0:醒目    1:鲜橙多    2:潘石榴    3:娃哈哈    4:绿茶    5:红茶    6:可口可乐
然后下边直接写出：
请输入你想要饮料的序号：
您的操作不正确！

Answer 6

判断写反了啊，呵呵import java.util.Scanner;public class SellGoodsSys { /**
 * @param args
 */
private String[] goodsArray;
public static void main(String[] args) {
SellGoodsSys goods = new SellGoodsSys();
System.out.println();
Scanner scan = new Scanner(System.in);
System.out.print("请输入一个0~6之间的数字：");

if(scan.hasNextInt()){
int a = scan.nextInt();
if(a>=0&&a<=6){
System.out.println(goods.goodsArray[a]);
}else{
System.out.println("您的操作不正确！！！");
}
}else{
System.out.println("您输入的不是整数");
}
}

public SellGoodsSys(){
goodsArray = new String[]{"0:醒目","1:鲜橙多","2:潘石榴","3:娃哈哈","4:绿茶","5:红茶","6:可口可乐"};
System.out.print("商品：");
for(int i=0;i<goodsArray.length;i++){
System.out.print(" "+goodsArray[i]);
}
}
}
 

Answer 7

if ((a < 0) && (a > 6))           
写错了
应为
if(（a>=0）&&(a<=6))