????1.????????==??equals
????==:??????????ж?????????????????????(???????)
????equals?????????
????2.?????????????????
????str.spilt("\s+")
??????????????????""??????" "??tab????" "?????" "??
????3.?????????????
????3.1common???stringutils???????
????Stringstr="abcd";
????Stringrepeated=StringUtils.repeat(str??3);//abcdabcdabcd
????3.2StringBuilder???????????
Stringsrc="name";
intlen=src.length();
intrepeat=5;
StringBuilderbuilder=newStringBuilder(len*repeat);
for(inti=0;i<repeat;i++){
builder.append(src);
}
Stringdst=builder.toString();
????4.?????????е????????????????
???????????е????????
????intn=StringUtils.countMatches("11112222"??"1");
?????????????char[]?????????