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String s1 = 'Testing String';
String s2 = 'Concatenation Performance';
String s3 = s1 + ' ' + s2;
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s.append('Testing String');
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s.append('Concatenation Performance');
String s3 = s.toString();
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if (str == null) {
str = String.valueOf(str);
}
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int newcount = count + len;
if (newcount > value.length) expandCapacity(newcount);
str.getChars(0, len, value, count);
count = newcount; return this;
}
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