变量的原始类型在编译期间没有字段x

Question

I wrote a java program to compare two strings and at the time of compilation I am getting the error: The primitive type int of length1 does not have a field j Syntax error on token ",", . expected

Here is my program:

import java.util.*;

public class StringCompare {
    public static void main(String args[]){
        String str1, str2;
        int i,j, flag=0;
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the first string \n");
        str1=sc.nextLine();
        System.out.println("Enter the next string \n");
        str2=sc.nextLine();
        int length1=str1.length();
        int length2=str2.length();
        if(length1!=length2){
            System.out.println("The strings are not equal");
        }
        else
        {
            for(i=1,j=1;i<=length1, j<=length2;i++,j++){
                if(str1.charAt(i)!=str2.charAt(j)){
                    flag=1;
                    break;
                }
            }
            if(flag==0)
                System.out.println("The strings are equal \n");
            else
                System.out.println("The strings are not equal \n");
        }
    }
}

Answer 1

You cannot have a comma-seperated list of conditions in the middle of your for loop. You must have an expression that evaluates to true or false only.

You are free to have a comma-seperated list of initialization statements in the first part of your for loop, which is probably what you were thinking.

Read here for more: https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html

Answer 2

Because length1 and length2 has the same value in the for loop you only need the i variable. Simplify it to be like:

for (i = 0; i < length1; i++){
    if(str1.charAt(i) != str2.charAt(i)){
        flag = 1;
        break;
    }
}

EDIT: you also have a bug in your code. Lets say your strings length is 3 and your loop goes from 1 to 3, when str1.charAt(3) is called (i==3) it will crash. You need to start from 0 and stop to 2 (i < length1).

Answer 3

The reason for string index of of range error at for for (i = 0; i < length1; i++) is that the compiler is trying to access a point in the string which does not exist. It should be for(i=1;i<=length1-1;i++)