How to enter numbers in java

Java's Scanner class provides nextInt, nextFloat, nextDouble and other methods, which can read numbers of specified types like scanf in C language. (Recommended: java video tutorial)

First define a Scanner object:

Scanner sn = new Scanner(System.in);

Use sn.nextInt to read integer numbers. Note that if the input is not an integer number, This function throws InputMismatchException and should be caught.

  System.out.print("请输入一个整数：");  
  try{   
       intVal = sn.nextInt();   
       System.out.println("你输入了：" + intVal);  
       }
       catch(InputMismatchException e){   
             System.out.println("必须输入整数！");  
       }

Use sn.nextFloat to read single-precision floating point numbers. If the input is not a number, an InputMismatchException will also be thrown and should be caught.

System.out.print("请输入一个浮点数：");  
       try{  
        floatVal = sn.nextFloat();   
        System.out.println("你输入了：" + floatVal);  
        }
        catch(InputMismatchException e){  
         System.out.println("必须输入数！"); 
        }

Use sn.nextDouble to read double-precision floating-point numbers. The operation is similar to single-precision.

System.out.print("请输入一个浮点数："); 
 try{  
  doubleVal = sn.nextDouble();   
  System.out.println("你输入了：" + doubleVal); 
   }catch(InputMismatchException e) 
    {  
     System.out.println("必须输入数！");  
    }

The stream should be closed after use: sn.close();

For more java knowledge, please pay attention to the java basic tutorial column.

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