JAVA语言编程中如何使用表达式

JAVA 正则表达式涉及的三个类:

StringPatternMatcher

Pattern是要匹配的模式Matcher是匹配的结果

例如:Pattern p = plie([az]{});

Matcher m = pmather(abc);

要想在正则表达式中匹配一个反斜线用四个反斜线表示: \\matches(\\\\);

匹配空白行 \nmatches(^[\\s&&[^\\n]]*\\n$);

找出匹配结果在整个字符串的开始位置和结束位置

Pattern p = plie(\\d{});

String a = ;

Matcher m = pmatcher(s);

mmatches() // 匹配整个字符串所以这里是false;

mreset();

while(mfind()) // 找一个和这个模式所匹配的子串

{

Systemoutprintln(mstart() + To + mend());

}

将匹配到的java都转换成大写的

Pattern p = plie(java PatternCASE_INSENSITIVE);

Matcher m = pmatcher(java Java JaVa IloveJava You HateJaVA);

mreplaceAll(JAVA);

将匹配偶数个转换为大写奇数个转换为小写

package zxtest;

import javautilregexMatcher;

import javautilregexPattern;

public class TestPattern

{

public static void main(String[] args)

{

StringBuffer newString = new StringBuffer();

String isPatternString = java Java JaVa IloveJava You HateJaVA;

Pattern p = pile(java PatternCASE_INSENSITIVE);

Matcher m = pmatcher(isPatternString);

int i = ;

while(mfind())

{

i++;

if (i % == )

{

mappendReplacement(newString java);

}

else

{

mappendReplacement(newString JAVA);

}

}

mappendTail(newString);

Systemoutprintln(newString);

}

}

输出结果:JAVA java JAVA Ilovejava You HateJAVA

Java正则表达式分组:

private static void testGroup()

{

String s = afdsafijiikfsdfaf;

Pattern p = pile((\\d{})([az]{})); // 组:(\\d{}) 组:([az]{})

Matcher m = pmatcher(s);

while(mfind())

{

Systemoutprintln(Group: + mgroup() + Group: + mgroup() + Group: + mgroup());

}

}

输出结果:

Group: afdsaf Group: Group: afdsaf

Group: ijii Group: Group: ijii

Group: k Group: Group: k

Group: fsdfaf Group: Group: fsdfaf