for loop with comparing to set of arrays

Question

Q. what is the right condition for DISPLAYING ONLY equal elements in my array.

heres the code.

    int num[]=new int[5];
    int numm[]=new int[5];

    for(int x=0;x<num.length;x++){
        num[x]=Integer.parseInt(JOptionPane.showInputDialog("Enter Values for num["+(x+1)+"]"));
    }

    for(int x1=0;x1<num.length;x1++){
        num[x1]=Integer.parseInt(JOptionPane.showInputDialog("Enter Values for num1["+(x1+1)+"]"));
    }

    String tosho="";
        for(int a=0;a<num.length;a++){
            for(int a1=0;a1<numm.length;a1++){
            if(num[0]==numm[0]){
              num[0]=numm[0];}


            else if(num[1]==numm[1]){
                num[1]=numm[1];}

            else if(num[2]==numm[2]){
                num[2]=numm[2];}

            else if(num[3]==numm[3]){
                num[3]=numm[3];}

            else if(num[4]==numm[4]){
                num[4]=numm[4];}       
        }

    }tosho+=(num[0])+""+(num[1])+""+(num[2])+""+(num[3])+""+(num[4]);

    JOptionPane.showMessageDialog(null, "both "+tosho+" found in array.");

when I input 1,2,3,4,5 in first aary

then 1,22,3,4,5 in second array

still it display the 2 or 22, even though they are not equal,,,

I would use ArrayList.contains() to find the intersection, and display that ... — Stewart
– Stewart, Commented Nov 20, 2013 at 13:55

Prabhakaran Ramaswamy · Accepted Answer · 2013-11-20 13:59:50Z

3

Why so long code

    for(int a=0;a<num.length;a++){
        for(int a1=0;a1<numm.length;a1++){
        if(num[0]==numm[0]){
          num[0]=numm[0];}


        else if(num[1]==numm[1]){
            num[1]=numm[1];}

        else if(num[2]==numm[2]){
            num[2]=numm[2];}

        else if(num[3]==numm[3]){
            num[3]=numm[3];}

        else if(num[4]==numm[4]){
            num[4]=numm[4];}       
    }
   }

do like this

    List <Integer> matchedElements = new ArrayList<Integer>();
    for(int a=0;a<num.length;a++){
        for(int a1=0;a1<numm.length;a1++){
            if(num[a]==numm[a1]){
                matchedElements.add(num[a]);
           }
        }
    }
    Integer[] mached = matchedElements.toArray(new Integer[matchedElements.size()]);
    System.out.println(Arrays.toString(mached));

edited Nov 20, 2013 at 13:59

answered Nov 20, 2013 at 13:52

Prabhakaran Ramaswamy

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1 Comment

Caleryn Over a year ago

Yes it can be shortened but is the the logic not still wrong? for the problem described.

The Guy with The Hat · Accepted Answer · 2013-11-20 14:28:41Z

2

num[x1]=Integer.parseInt(JOptionPane.showInputDialog("Enter Values for num1["+(x1+1)+"]"));

maybe numm[x1]?

You can use this code to fill tosho:

String tosho="";
for(int a=0;a<num.length;a++) {
    if(num[a]==numm[a]) {
        tosho+=num[a]+",";
    }
}

edited Nov 20, 2013 at 14:28

The Guy with The Hat

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answered Nov 20, 2013 at 14:00

Ruslan Ostafiichuk

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1 Comment

jarnthrax Over a year ago

big mistake for numm[], hahaha and thank you for this code.

Lucas · Accepted Answer · 2013-11-20 13:56:05Z

2

you start your if squence with

if(num[0]==numm[0]){
          num[0]=numm[0];}

and then you are using ELSE which means that it will be evaluated ONLY if the first if is not executing. It means that after you change the first element of the array, no other will be changed as there will be no ELSE since num[0] will equal numm[0]. Remove all "else" words and it should work.

answered Nov 20, 2013 at 13:56

Lucas

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2 Comments

jarnthrax Over a year ago

but still it does not display the ONLY equal elements.

Lucas Over a year ago

that's because you don't even need those two loops if you check every element of the array manually (all those ifs)

Andrei Nicusan · Accepted Answer · 2013-11-20 14:02:49Z

2

These two nested loops

for(int a=0;a<num.length;a++){
    for(int a1=0;a1<numm.length;a1++){
    ...

are useless.

You're not using in any way the variables a and a1.

Instead, you could simply iterate form 0 to array length and check the elements with same index for equality.

answered Nov 20, 2013 at 14:02

Andrei Nicusan

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Comments

erencan · Accepted Answer · 2013-11-20 14:08:54Z

The assignment is wrong. you never assign values to numm variable.

The nested loops are no effect in the code. there no usage of a and a1 loop variable.

I added an additional array to store same values called sameValues and assign same values.

int num[]=new int[5]; int numm[]=new int[5]; int sameValues[] = new int[5];

for(int x=0;x<num.length;x++){
        num[x]=Integer.parseInt(JOptionPane.showInputDialog("Enter Values for num["+(x+1)+"]"));
        }

for(int x1=0;x1<num.length;x1++){
        numm[x1]=Integer.parseInt(JOptionPane.showInputDialog("Enter Values for num1["+(x1+1)+"]"));
        }

int counter = 0;
String tosho="";
for(int a=0;a<num.length;a++){
        for(int a1=0;a1<numm.length;a1++){
                if(num[a] == numm[a1]){
                        sameValues[counter] = num[a];
                        counter++;
                 }
        }
}

for(int x=0;x<counter ;x++){
        tosho+=(num[x]) + " ";
}

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