Java-Convert String to int when using BufferedRead

问题:

How do you convert a String to int when using BufferedReader? as far as i remember,its something like below:

System.out.println("input a number");

int n=Integer.parseInt(br.readLine(System.in));

but for some reason,its not working.

the error message says:

no suitable method found for readLine(java.io.InputStream)

it also says br.readLine is not applicable

回答1:

An InputStreamReader needs to be specified in the constructor for the BufferedReader. The InputStreamReader turns the byte streams to character streams. As others have mentioned be cognizant of the exceptions that can be thrown from this piece of code such as an IOException and a NumberFormatException.

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.println("input a number");
int n = Integer.parseInt(br.readLine());

回答2:

When using BufferedReader you have to take care of the exceptions it may throw. Also, the Integer.parseInt(String s) method may throw an NumberFormatException if the String you're providing cannot be converted to Integer.

try {
   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
   while ((thisLine = br.readLine()) != null) {
     System.out.println(thisLine);
     Integer parsed = Integer.parseInt(thisLine);
     System.out.println("Parsed integer = " + parsed);
   } 
 } catch (IOException e) {
    System.err.println("Error: " + e);
 } catch (NumberFormatException e) {
    System.err.println("Invalid number");
 }

回答3:

try this

BufferedReader br = new BufferedReader(System.in);
String a=br.readLine()
Integer x = Integer.valueOf(a);
System.out.println(x);//integer value

回答4:

try this way

BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
 String input = reader.readLine();
 int n=Integer.parseInt(input);

回答5:

Try this:

  BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
   System.out.println("input a number");
try{  
    int n = Integer.parseInt(br.readLine());
    } catch (IOException e) {e.printStackTrace();}

回答6:

DataInputStream br=new DataInputStream(System.in);
System.out.println("input a number");
int n=Integer.parseInt(br.readLine(System.in));