TA貢獻(xiàn)2016條經(jīng)驗(yàn) 獲得超9個(gè)贊
不知道你說(shuō)的實(shí)現(xiàn)是怎么個(gè)實(shí)現(xiàn)？如果只是調(diào)用的話(huà) str.subString(begin,end)就可以了，如果是java的底層實(shí)現(xiàn)的話(huà)，下面是來(lái)自java.lang.String的代碼:
public String substring(int beginIndex, int endIndex) { if (beginIndex < 0) { throw new StringIndexOutOfBoundsException(beginIndex); } if (endIndex > count) { throw new StringIndexOutOfBoundsException(endIndex); } if (beginIndex > endIndex) { throw new StringIndexOutOfBoundsException(endIndex - beginIndex); } return ((beginIndex == 0) && (endIndex == count)) ? this : new String(offset + beginIndex, endIndex - beginIndex, value); } |
然后調(diào)用String的一個(gè)私有構(gòu)造器:
// Package private constructor which shares value array for speed. String(int offset, int count, char value[]) { this.value = value; this.offset = offset; this.count = count; } |
TA貢獻(xiàn)1865條經(jīng)驗(yàn) 獲得超7個(gè)贊
給你個(gè)例子,你參考下
public class $ { public static void main(String[] args) { String str = "abcdefg"; System.out.println(substring(str, 0, 1)); } private static String substring(String str, int begin, int end) { char[] ch = str.toCharArray(); StringBuffer buf = new StringBuffer(); for (int i = begin; i < end; i++) { buf.append(ch[i]); } return buf.toString(); }} |
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