How click Next Button and Back Button in array index

Question

I'm creating an app on android for viewing the image when I select the next button to show the new image and the back button to show previous image but when the press the next button to the maximum index , i want it to show the start from first image index and when the press the back button to the minimum index, i want it to show the start from maxminum image index. I have problem when i click the back button go to 0 index i want it show the image from the final index and also when i click the next button go to final index i want it show the from the 0 index. *

    if (v == btn_back) {
        if((currentimageindex)!=0){
            imageview.setImageResource(IMAGE_IDS[currentimageindex]);
               mp = MediaPlayer.create(this, myMusic[currentsoundindex]);
               mp.start();
              --currentimageindex;
              --currentsoundindex;
           }
          if((currentimageindex)==0){
                    imageview.setImageResource(IMAGE_IDS[currentimageindex]);
                       mp = MediaPlayer.create(this, myMusic[currentsoundindex]);
                       mp.start();
              --currentimageindex;
              --currentsoundindex;}
    if(v== btn next){*******}

weston · Accepted Answer · 2015-06-15 09:13:38Z

2

Replace --currentimageindex with:

currentimageindex = (currentimageindex + IMAGE_IDS.length -1) % IMAGE_IDS.length;

When the index is 0 this will make it will wrap around to IMAGE_IDS.length-1.

Note, for going forward you only need do this:

currentimageindex = (currentimageindex + 1) % IMAGE_IDS.length;

answered Jun 15, 2015 at 9:13

weston

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