我已经编写了一个Java程序来使用switch语句表示DFA,但它不会接受它应该做的单词。我尝试添加一个单独的案例来将最终状态发送到,以输出"单词已接受"或"单词未接受",但这不起作用。接受的单词示例应为:谷歌gglexxgooooooglexeg
到目前为止我的代码:
public static void main(String[] args) {
System.out.println("Enter a word to run on the DFA:");
Scanner scanner = new Scanner(System.in);
String string = scanner.nextLine();
int state = 1;
for (char s : string.toCharArray()) {
switch (state) {
case (1): {
if (s == 'e' || s == 'l' || s == 'o' || s == 'x') {
state = 1;
} else if (s == 'g') {
state = 2;
}
}
break;
case (2): {
if (s == 'e' || s == 'l' || s == 'x') {
state = 1; {
} if (s == 'o') {
state = 2;
} else if (s == 'g') {
state = 3;
}
}
}
break;
case (3): {
if (s == 'e' || s == 'x') {
state = 1; {
} if (s == 'g' || s == 'o') {
state = 2;
} else if (s == 'l') {
state = 4;
}
}
break; }
case (4): {
if (s == 'g' || s == 'l' || s == 'o' || s == 'x') {
state = 1;
} else if (s == 'e') {
state = 5;
}
break; }
case (5): {
if (s == 'e' || s == 'g' || s == 'l' || s == 'o' || s == 'x') {
state = 5;
} else {
state = 5;
}
break; }
}
}
if (state == 5) {
System.out.println("Word accepted");
} else {
System.out.println("Word not accepted");
scanner.close();
}
}
p.S:我知道else语句是否很慢,但对于这样的小程序来说,它似乎足够快了。
您的代码中有很多问题。试着正确缩进代码,看看括号的打开和关闭位置。
例如:
- 在案例1和案例2中,您的休息时间在案例块之外
- 在
state = 1; {}
语句之后的情况2和情况3中有一个空块 - 在情况2和3中,您的
if-else if
包含在第一个if
语句中。考虑到您的输入和预期输出,我认为这是错误的
以下是工作的格式化代码:
for (char s : string.toCharArray()) {
switch (state) {
case (1): {
if (s == 'e' || s == 'l' || s == 'o' || s == 'x') {
state = 1;
} else if (s == 'g') {
state = 2;
}
break;
}
case (2): {
if (s == 'e' || s == 'l' || s == 'x') {
state = 1;
} else if (s == 'o') {
state = 2;
} else if (s == 'g') {
state = 3;
}
break;
}
case (3): {
if (s == 'e' || s == 'x') {
state = 1;
} else if (s == 'g' || s == 'o') {
state = 2;
} else if (s == 'l') {
state = 4;
}
break;
}
case (4): {
if (s == 'g' || s == 'l' || s == 'o' || s == 'x') {
state = 1;
} else if (s == 'e') {
state = 5;
}
break;
}
case (5): {
if (s == 'e' || s == 'g' || s == 'l' || s == 'o' || s == 'x') {
state = 5;
} else {
state = 5;
}
break;
}
}
}