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问题描述
import java.util.Scanner;
public class Lab5
{
public static void main (String[]args)
{
Scanner in = new Scanner(System.in);
System.out.println("How big is the multiplication");
int choice = in.nextInt();
while(choice>=1 && choice<=20)
{
System.out.print("\nX\t");
for(int x = 1; x <= choice; x++)
{
System.out.print(x+"\t");
System.out.print("\n\t");
}
for( int l=choice; l<=choice; l++)
{
System.out.print("-------");
System.out.println();
}
for (int j = 1; j <= choice; j++)
{
System.out.print("row"+choice+"|\t");
for (int i = 1; i <= choice; i++)
{
System.out.print(i * j + "\t");
}
System.out.println();
}
}
}
}
推荐答案
int choice = in.nextInt();
while(choice>=1 && choice<=20)
{
...
您的循环基于变量choice
中返回的值.但是,在循环结束时,您不会获得新值,也没有任何退出循环的方法.更好的方法是:
Your loop is based in the value returned in the variable choice
. However, at the end of the loop you do not get a new value or have any way of breaking out of the loop. A better way would be something like:
int choice;
do
{
System.out.println("How big is the multiplication");
choice = in.nextInt();
if (choice < 1 || choice > 20)
break; // exit the loop if choice out of range
// all other code here
} while(choice > 0);
while(choice>=1 && choice<=20)
{
System.out.print("\nX\t");
for(int x = 1; x <= choice; x++)
{
System.out.print(x+"\t");
System.out.print("\n\t");
}
for( int l=choice; l<=choice; l++)
{
System.out.print("-------");
System.out.println();
}
for (int j = 1; j <= choice; j++)
{
System.out.print("row"+choice+"|\t");
for (int i = 1; i <= choice; i++)
{
System.out.print(i * j + "\t");
}
System.out.println();
}
choice++; // Added this line of code as fix
}
/*---------------------------------------------------------------------------
// AUTHOR: (Put your name here)
// FILENAME: Lab5.java
// SPECIFICATION: This program is for practicing nested loops.
// The first task is to print a multiplication table
// whose size is specified by the user.
// The second (optional, no extra credit, just for fun)
// task is to encode a string entered by the user.
// The encryption you will use is as follows: in the ith
// word, shift every letter up by i (so if the sentence
// is "abc abc abc", it becomes "bcd cde def").
// INSTRUCTIONS: Read the following code skeleton and add your own code
// according to the comments. Ask your TA or your class-
// mates for help and/or clarification. When you see
// //--> or ??? that is where you need to add code.
// LAB LETTER: (Put your Lab Letter here)
//-------------------------------------------------------------------------*/
// Import required package (Scanner)
//-->
//Declare class (Lab5)
//-->
//-->
//Declare the main method
//-->
//-->
//Declare some variables: a Scanner (and initialize) and an integer that holds
//the user's choice of how big the multiplication table is.
//-->
//-->
//For the second task (optional) declare the following:
//an integer variable to keep track of what word we're currently operating on,
//a String array that holds each word int he user's sentence separately
//a String that holds the encrypted text,
//Give the strings initial values of "" (empty string but not null),
//and give the first integer variable an initial value of 0
//-->
//-->
//-->
//make a do while loop that will repeat until the user enters a valid
//input (an integer from 1 to 20).
???
{
//Ask the user how large to make the multiplication table
//-->
//Read in the user's input
//-->
//output the multiplication table if the user's input is within the
//appropriate range (1-20)
???(???)
{
//Print out the following string used for formatting the table "\nX\t"
//use print, not println
//-->
//make a for loop that prints each of the numbers from 1 to the user-specified number
//putting a tab '\t' character in between each number (all on the same line)
???(???; ???; ???)
//-->
//Print out the following string used for formatting the table "\n\t"
//use print, not println
//-->
//make a for loop that prints out the string "--------" (on the same line)
//a number of times equal to the user specified size of the multiplication
//table (more formatting)
???(???; ???; ???)
//-->
//Print a blank line
//-->
//make a for loop that will range a variable i from 1 to the user-specified
//size of the multiplication table. At the start of each row (the outer loop),
//you should print the current row number and the string "|\t" for formatting
//Inside of that for loop, do the same for
//a variable j. Each table entry will be i*j and you should print this as well
//as tab character '\t' after each entry. Also, after each row is done, you
//should print a blank line.
???(???; ???; ???)
{
System.out.print(??? + "|\t");
???(???; ???; ???)
{
System.out.print(??? + "\t");
}
//Print a blank line
//-->
}
}
//otherwise print out an error telling the user the input is out of range
???
{
//-->
}
}???(???);
/*
请参阅最后一部分
See this last part
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