如何显示数组的位置

Question

Your program should display whether the inputted integer value is found in list, how many of it is in list, and what are their locations in list? sample

List : 1 3 2 5 7 8 5 6 9 4

Input value to search in List: 9
The value 9 is in List!
There are 4 of it in List.
Located at: list[4], list[5], list[6], list[8]

this is my code

import java.io.*; 
public class List{ 
  public static void main(String[] args){ 
    int list[] = new int[10]; 
    int i, num = 0, num1=0; 
    String input = " "; 
    BufferedReader in = new BufferedReader(new 
                               InputStreamReader(System.in)); 

    for(i = 0; i < 10; i++){ 
      list[i] = 0; 
    } 
    for(i = 0; i < 10; i++){ 
      System.out.print("Input value for list[" + i + "] = "); 
      try{ 
        input = in.readLine();         
        num = Integer.parseInt(input); 
        list[i] = num; 
      for(i = 0; i < 10; i++){ 
        System.out.println("list[" + i + "] = " +list[i]); 
      } 
      for (int b = 0; b < list.length; ++b) {
        if (num1 == list[b]) {
          returnvalue = b;
          break;
        }
      }
      System.out.print("Input value for list");
      input = in.readLine();
      num1 = Integer.parseInt(input);
    }catch(IOException e){} 
      System.out.println("the position is" + returnvalue);
    }
  } 
} 

I think the position that is returning is not accurate can you help me?

Answer 1

This will do what you want... Modify the System.out.println(); part according to your need.

public static void main(String[] args) throws IOException {
int list[] = new int[10];
int i, num = 0, num1 = 0;
int returnvalue = 0;
String input = " ";
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

for (i = 0; i < 10; i++) {
    list[i] = 0;
    }
for (i = 0; i < 10; i++) {
    System.out.print("Input value for list[" + i + "] = ");    
    input = in.readLine();
    num = Integer.parseInt(input);
    list[i] = num;
    }

for (i = 0; i < 10; i++) {
    System.out.println("list[" + i + "] = " + list[i]);
    }
System.out.print("Input value for checking in  list ");
input = in.readLine();
num1 = Integer.parseInt(input);

boolean flag = false;
int[] arr = new int[10];
int count= 0;
for (int b = 0; b < list.length; ++b) {
  if (num1 == list[b]) {              
      flag = true;
      arr[count]=b;
      count++;
      }
}
if(flag)
{
   System.out.println("The value "+num1+" is in List!");
   System.out.println("There are "+count+" of it in List");
   System.out.print("Located at: ");
   for(int j=0; j<count;j++)
   {
    System.out.print(" List["+arr[j]+"]");
   }
} 
else {
System.out.print(" Element Not found");
}

}

The Console Part for input output is...

Input value for list[0] = 4
Input value for list[1] = 5
Input value for list[2] = 6
Input value for list[3] = 4
Input value for list[4] = 5
Input value for list[5] = 6
Input value for list[6] = 5
Input value for list[7] = 4
Input value for list[8] = 4
Input value for list[9] = 6
list[0] = 4
list[1] = 5
list[2] = 6
list[3] = 4
list[4] = 5
list[5] = 6
list[6] = 5
list[7] = 4
list[8] = 4
list[9] = 6
Input value for checking in  list 4
The value 4 is in List!
There are 4 of it in List.
Located at:List[0] List[3] List[7] List[8]

Fixes in your code

1. A try block is either with a catch block or with a finally block or both.
2. Having two same variables in inner and outer loop is not good. In your case the outer loop will iterate just once. I think which is not needed.

Answer 2

There are two nested for loop where the loop control variable is same:

for(i = 0; i < 10; i++){ 
    System.out.print("Input value for list[" + i + "] = "); 
    ... 
    for(i = 0; i < 10; i++){
         System.out.println("list[" + i + "] = " +list[i]);
    }
    ...

So, the outer for loop will never iterate what you are expecting. Use a different loop control variable for the inside for loop.

Answer 3

here is my solution for your problem. no need to use that much of loops. you want to use only one foreach - How does the Java 'for each' loop work? (if you don't need to ask question again and agian). I was unable to test this lot :). But, I hope this will work.

import java.util.*;
class MyList{
public static void main(String arga[]){
    int array[] = {1,3,2,5,7,8,5,6,9,4};

    Scanner input = new Scanner(System.in);
    // recursively ask the question
    while(true){
        System.out.print("Enter the value to search in list: ");

        int value = input.nextInt();
        System.out.println();
        int i = 0;// to get the array index
        int count = 0; // to get how many 

        String list = "Located at: ";
        boolean isTrue = false; // to get entered value is in the list or not
        for(int a: array){
            if(a == value){
                isTrue = true;
                list += "list[" + i + "],";
                count++;
            }
            i++;
        }
        if(isTrue){
            //remove the last "," from the string
            list = list.substring(0, list.length() - 1);
            System.out.println("The value " + value +" is in List!");
            System.out.println("There are " + count +" of it in List.");
            System.out.println(list);
        }else{
            System.out.println("this value is not in the list");
        }
    }
}

}