Why can't use the same Span object to setSpan above twice?

Question

SpannableString ss = new SpannableString("aaaaa[1]bbbb[1]cccc[1]");

I need to replace all the [1] with a image. If I use the following code, only the last one is replaced by the image:

etShow = (EditText) findViewById(R.id.show);
SpannableString ss = new SpannableString("aaaaa[1]bbbb[1]cccc[1]");
int[] starts = new int[3];
int[] ends = new int[3];
int h = 0;
int k = 0;
for (int i = 0; i < ss.length(); i++) {
    if (ss.charAt(i) == '[') {
    starts[h] = i;
    h++;
    } else if (ss.charAt(i) == ']') {
    ends[k] = i;
    k++;
    }
    }

Drawable d = getResources().getDrawable(R.drawable.ic_launcher);
        d.setBounds(0, 0, 50, 50);
        ImageSpan im = new ImageSpan(d);

for(int i=0;i<3;i++){
        ss.setSpan(im, starts[i], ends[i]+1, Spannable.SPAN_INCLUSIVE_EXCLUSIVE);   
        }
etShow.getText().insert(0, ss);

If change to the following code， all the [1] are replaced by the image.

Drawable d = getResources().getDrawable(R.drawable.ic_launcher);
        d.setBounds(0, 0, 50, 50);
        ImageSpan im = new ImageSpan(d);
        ImageSpan im1 = new ImageSpan(d);
        ImageSpan im2 = new ImageSpan(d);
        //for(int i=0;i<3;i++){
//      ss.setSpan(im, starts[i], ends[i]+1, Spannable.SPAN_INCLUSIVE_EXCLUSIVE);
        ss.setSpan(im, starts[0], ends[0]+1, Spannable.SPAN_INCLUSIVE_EXCLUSIVE);
        ss.setSpan(im1, starts[1], ends[1]+1, Spannable.SPAN_INCLUSIVE_EXCLUSIVE);
        ss.setSpan(im2, starts[2], ends[2]+1, Spannable.SPAN_INCLUSIVE_EXCLUSIVE);
    //  }

How can explaint this?

score 10 · Accepted Answer · answered Oct 29 '12 at 09:49

10

I suspect that the span objects wind up as keys of a HashMap, inside the Spanned representation. Hence, reusing the same span object has the effect of replacing its prior use with a new use.

answered Oct 29 '12 at 09:49

CommonsWare

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score 5 · Answer 2 · answered Nov 23 '16 at 04:33

I read the Spannable source code these days and find this question by Google, so I want to paste some source code to answer this question.

The SpannableString implement by SpannableStringInternal and setSpan method is as follows.

/* package */ void setSpan(Object what, int start, int end, int flags) {
    ...
    int count = mSpanCount;
    Object[] spans = mSpans;
    int[] data = mSpanData;
    for (int i = 0; i < count; i++) {
        if (spans[i] == what) {
            int ostart = data[i * COLUMNS + START];
            int oend = data[i * COLUMNS + END];
            data[i * COLUMNS + START] = start;
            data[i * COLUMNS + END] = end;
            data[i * COLUMNS + FLAGS] = flags;
            sendSpanChanged(what, ostart, oend, nstart, nend);
            return;
        }
    }
    ...
}

When you pass same span by setSpan method, it will check if spans array have same one and replace old start and end value by news.

Why can't use the same Span object to setSpan above twice?

2 Answers2

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