[英]parsing for integers from user input in java?
I want to get a rational number from the user in the form 188/4 for example and end up with int 188 and int 4. what is an efficient way to do this in java? 我想以188/4的形式从用户那里得到一个有理数,并以int 188和int 4结尾。在Java中,有什么有效的方法? is stringTokenizer the best way?? stringTokenizer是最好的方法吗? or is there something like scanf in c?? 还是在c中有类似scanf的东西?
private int NUM;
private int DEN;
static Scanner s;
public Rational(){
s = new Scanner(System.in).useDelimiter("/");
System.out.println("Enter Rational number in the form of a/b:");
NUM = s.nextInt();
int d = s.nextInt();
if(d == 0){
throw new IllegalArgumentException();
}
else{
DEN = d;
}
}
when I run this my program freezes after I input a number 当我运行此程序时,输入数字后程序将冻结
Try something like this (assuming each fraction can be input on a separate line): 尝试这样的操作(假设每个分数可以在单独的行中输入):
s = new Scanner(System.in).useDelimiter("\n");
System.out.println("Enter Rational number in the form of a/b:");
String in = s.nextLine();
while (in.length() > 0) {
if (in.contains("/")) {
try {
NUM = Integer.parseInt(in.split("/")[0]);
DEN = Integer.parseInt(in.split("/")[1]);
} catch (Exception e){
throw new IllegalArgumentException("Fraction must contain numeric values only");
}
} else {
throw new IllegalArgumentException("Fraction must contain a '/' character");
}
System.out.println("NUM = " + NUM + " DEN = " + DEN);
in = s.nextLine();
}
Small tweaks... 小调整...
private int NUM;
private int DEN;
static Scanner s;
public Rational(){
System.out.println("Enter Rational number in the form of a/b:");
s = new Scanner(System.in);
String[] values = s.next().split("/");
NUM = Integer.parseInt(values[0]);
int d = Integer.parseInt(values[1]);
if(d == 0){
throw new IllegalArgumentException();
} else{
DEN = d;
}
}
The only way i could think about is to treat is as a string, remove the unnecessary "/" and then turn it back into a int with Integer.parseInt(); 我能想到的唯一方法是将其视为字符串,删除不必要的“ /”,然后使用Integer.parseInt()将其转换回int。
int NUM;
int DEN;
Scanner s;
s = new Scanner(System.in).useDelimiter("/");
System.out.println("Enter Rational number in the form of a/b:");
String enteredString = s.nextLine();
String firstString = "", secondString = "";
StringBuilder sb = new StringBuilder(enteredString);
boolean foundWeirdChar = false;
boolean firstChar = true;
char tempChar = '/';
for(int i = 0; i < sb.length(); i++) {
if(sb.charAt(i) == tempChar) {
foundWeirdChar = true;
}
if(!foundWeirdChar) {
firstString += sb.charAt(i);
}else {
if(firstChar) { // Because the first char will be "/"
firstChar = false;
}else{
secondString += sb.charAt(i);
}
}
}
int a = 0;
int b = 0;
try {
a = Integer.parseInt(firstString);
b = Integer.parseInt(secondString);
System.out.println("First int: " + a + "\nSecond int: " + b);
}catch(NumberFormatException ex) {
ex.printStackTrace();
}
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