String删除字符
String类没有提供删除的类方法,但删除字符又属于常见需求。
String st = "abcd";
一、删除特定字符
这个有点复杂。直接转载了,原文见 https://blog.csdn.net/linzhiqiang0316/article/details/90440696:
第一种方法
通过循环从前往后遍历,如果不是要删除的字符则加到处理后的字符串中,代码如下:
1 public String deleteCharString0(String sourceString, char chElemData) { 2 String deleteString = ""; 3 for (int i = 0; i < sourceString.length(); i++) { 4 if (sourceString.charAt(i) != chElemData) { 5 deleteString += sourceString.charAt(i); 6 } 7 } 8 return deleteString; 9 }
第二种方法
通过循环确定要删除字符的位置索引,然后通过分割字符串的形式,将子字符串拼接,注意最后一段子字符串和源字符串中没有要删除字符的情况,代码如下:
1 public String deleteCharString1(String sourceString, char chElemData) { 2 String deleteString = ""; 3 int iIndex = 0; 4 for (int i = 0; i < sourceString.length(); i++) { 5 if (sourceString.charAt(i) == chElemData) { 6 if (i > 0) { 7 deleteString += sourceString.substring(iIndex, i); 8 } 9 iIndex = i + 1; 10 } 11 } 12 if (iIndex <= sourceString.length()) { 13 deleteString += sourceString.substring(iIndex, sourceString.length()); 14 } 15 return deleteString; 16 }
第三种方法
原理同上,只不过查找要删除字符位置采用String类中的函数执行,效率不如上面的高,代码如下:
1 public String deleteCharString2(String sourceString, char chElemData) { 2 String deleteString = ""; 3 int iIndex = 0; 4 int tmpCount = 0; 5 do { 6 tmpCount = sourceString.indexOf(chElemData, iIndex); 7 if (tmpCount > 0) { 8 deleteString += sourceString.substring(iIndex, tmpCount); 9 } 10 if (tmpCount != -1) { 11 iIndex = tmpCount + 1; 12 } 13 } while (tmpCount != -1); 14 if (iIndex <= sourceString.length()) { 15 deleteString += sourceString.substring(iIndex, sourceString.length()); 16 } 17 return deleteString; 18 }
第四种方法
原理与上方基本一致,只不过这次采用倒序方式,这里的坑就更多了,一定要注意索引的取值范围和是否合法,代码如下:
1 public String deleteCharString3(String sourceString, char chElemData) { 2 String deleteString = ""; 3 int iIndex = sourceString.length(); 4 int tmpCount = 0; 5 do { 6 tmpCount = sourceString.lastIndexOf(chElemData, iIndex - 1); 7 if (tmpCount < sourceString.length() && tmpCount >= 0) { 8 deleteString = sourceString.substring(tmpCount + 1, iIndex) + deleteString; 9 } 10 if (tmpCount != -1) { 11 iIndex = tmpCount; 12 } 13 } while (tmpCount != -1); 14 if (iIndex >= 0) { 15 deleteString = sourceString.substring(0, iIndex) + deleteString; 16 } 17 18 return deleteString; 19 }
第五种方法
通过采用正则的方式和replaceAll函数,本种方法要注意特殊字符,例如正则中的 “.”字符,需要对特殊字符进行转义,代码如下:
1 public String deleteCharString4(String sourceString, char chElemData) { 2 String deleteString = ""; 3 final String strTable = "|^$*+?.(){}\\"; 4 String tmpRegex = "["; 5 for (int i = 0; i < strTable.length(); i++) { 6 if (strTable.charAt(i) == chElemData) { 7 tmpRegex += "\\"; 8 break; 9 } 10 } 11 tmpRegex += chElemData + "]"; 12 deleteString = sourceString.replaceAll(tmpRegex, ""); 13 return deleteString; 14 }
第六种方法
采用正则的方式将字符串分割成几个子字符串,再将子字符串进行拼接,代码如下:
1 public String deleteCharString5(String sourceString, char chElemData) { 2 String deleteString = ""; 3 final String strTable = "|^$*+?.(){}\\"; 4 String tmpRegex = "["; 5 for (int i = 0; i < strTable.length(); i++) { 6 if (strTable.charAt(i) == chElemData) { 7 tmpRegex += "\\"; 8 break; 9 } 10 } 11 tmpRegex += chElemData + "]"; 12 String[] tmpStringArray = sourceString.split(tmpRegex); 13 for (int i = 0; i < tmpStringArray.length; i++) { 14 deleteString += tmpStringArray[i]; 15 } 16 return deleteString; 17 }
第七种方法
将字符编程可读序列,在通过 String 类中的方法替换,代码如下:
1 public String deleteCharString6(String sourceString, char chElemData) { 2 String tmpString = ""; 3 tmpString += chElemData; 4 tmpString.subSequence(0, 0); 5 String deleteString = ""; 6 deleteString = sourceString.replace(tmpString, deleteString.subSequence(0, 0)); 7 return deleteString; 8 }
第八种方法
把原字符串转化为字符数组,然后原理与直接插入排序原理类似,代码如下:
1 public String deleteCharString7(String sourceString, char chElemData) { 2 String deleteString = ""; 3 char[] Bytes = sourceString.toCharArray(); 4 int iSize = Bytes.length; 5 for (int i = Bytes.length - 1; i >= 0; i--) { 6 if (Bytes[i] == chElemData) { 7 for (int j = i; j < iSize - 1; j++) { 8 Bytes[j] = Bytes[j + 1]; 9 } 10 iSize--; 11 } 12 } 13 for (int i = 0; i < iSize; i++) { 14 deleteString += Bytes[i]; 15 } 16 return deleteString; 17 }
第九种方法
原理与 第一种方法 类似,本次采用 stringBuffer 类中的 append 方法进行操作,我认为效率应该高于第一种。
1 public String deleteCharString8(String sourceString, char chElemData) { 2 StringBuffer stringBuffer = new StringBuffer(""); 3 for (int i = 0; i < sourceString.length(); i++) { 4 if (sourceString.charAt(i) != chElemData) { 5 stringBuffer.append(sourceString.charAt(i)); 6 } 7 } 8 return stringBuffer.toString(); 9 }
第十种方法
采用 stringBuffer 类中的 replace and indexOf 方法(_ 故意凑方法),代码如下:
1 public String deleteCharString9(String sourceString, char chElemData) { 2 String tmpString = ""; 3 tmpString += chElemData; 4 StringBuffer stringBuffer = new StringBuffer(sourceString); 5 int iFlag = -1; 6 do { 7 iFlag = stringBuffer.indexOf(tmpString); 8 if (iFlag != -1) { 9 stringBuffer = stringBuffer.replace(iFlag, iFlag + 1, ""); 10 } 11 } while (iFlag != -1); 12 return stringBuffer.toString(); 13 }
第十一种方法
采用 stringBuffer 类中的 deleteCharAt 和 indexOf 直接删除
1 public String deleteCharString10(String sourceString, char chElemData) { 2 String tmpString = ""; 3 tmpString += chElemData; 4 StringBuffer stringBuffer = new StringBuffer(sourceString); 5 int iFlag = -1; 6 do { 7 iFlag = stringBuffer.indexOf(tmpString); 8 if (iFlag != -1) { 9 stringBuffer.deleteCharAt(iFlag); 10 } 11 } while (iFlag != -1); 12 return stringBuffer.toString(); 13 }
二、删除指定位置字符
这个简单。假设要去除index 2的字符
1.用StringBuffer.remove(int index)
String st = "abcd";
StringBuffer sb = new StringBuffer(st); // String 转为 StringBuffer
sb.remove(2); // 用StringBuffer中的remove方法删除指定位置字符
String re1 = sb.toString(); // StringBuffer 转回 String
System.out.println(re1); // abd
2.用String类的subString方法拼接
String st = "abcd";
String re2 = st.substring(0, 2) + st.substring(2 + 1);
System.out.println(re2); // abd