第六章JAVA常用类.docx
《第六章JAVA常用类.docx》由会员分享,可在线阅读,更多相关《第六章JAVA常用类.docx(19页珍藏版)》请在冰豆网上搜索。
第六章JAVA常用类
importjava.util.regex.*;
publicclassTestString{
publicstaticvoidmain(String[]args){
//Strings="AaaaABBBBcc&^%adfsfdCCOOkk99876_haHA";
//intlCount=0,uCount=0,oCount=0;
/*
for(inti=0;icharc=s.charAt(i);
if(c>='a'&&c<='z'){
lCount++;
}elseif(c>='A'&&c<='Z'){
uCount++;
}else{
oCount++;
}
}
*/
/*
StringsL="abcdefghijklmnopqrstuvwxyz";
StringsU="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
for(inti=0;icharc=s.charAt(i);
if(sL.indexOf(c)!
=-1){
lCount++;
}elseif(sU.indexOf(c)!
=-1){
uCount++;
}else{
oCount++;
}
}
*/
/*
for(inti=0;icharc=s.charAt(i);
if(Character.isLowerCase(c)){
lCount++;
}elseif(Character.isUpperCase(c)){
uCount++;
}else{
oCount++;
}
}
System.out.println(lCount+""+uCount+""+oCount);
*/
Strings="sunjavahpjavaokjavajjavahahajavajavagoodjava";
StringsToFind="java";
intcount=0;
intindex=-1;
while((index=s.indexOf(sToFind))!
=-1){
s=s.substring(index+sToFind.length());
count++;
}
System.out.println(count);
}
}
//*************************************************
publicclassTestStringCase{
publicstaticvoidmain(String[]args){
Strings="ABAabb$&^$#BAAb898B#@%aa";
intcU=0,cL=0,cO=0;
for(inti=0;icharc=s.charAt(i);
if(c>='A'&&c<='Z'){
cU++;
}elseif(c>='a'&&c<='z'){
cL++;
}else{
cO++;
}
}
System.out.println("大写:
"+cU);
System.out.println("小写:
"+cL);
System.out.println("其他:
"+cO);
}
}
//*************************************************
/
在windows和linux系统下都写“/”最保险
\这个代表转义字符,\\两个连着写代表一个\,
packagebjsxt;
importjava.io.*;
publicclassTestFile{
publicstaticvoidmain(String[]args){
Stringseparator=File.separator;//使用指定的文件分割符
Stringfilename="myfile.txt";
Stringdirectory="mydir1"+separator+"mydir2";
//Stringdirectory="mydir1/mydir2";
//Stringdirectory="mydir1\\mydir2";
Filef=newFile(directory,filename);
if(f.exists()){
System.out.println("文件名:
"+f.getAbsolutePath());
System.out.println("文件大小:
"+f.length());
}else{
f.getParentFile().mkdirs();
try{
f.createNewFile();
}catch(IOExceptione){
e.printStackTrace();
}
}
}
}
importjava.io.*;
publicclassFileList{
publicstaticvoidmain(String[]args){
Filef=newFile("d:
/A");
System.out.println(f.getName());
tree(f,1);
}
privatestaticvoidtree(Filef,intlevel){//leven是递归的层数
StringpreStr="";
for(inti=0;ipreStr+="";
}
File[]childs=f.listFiles();
for(inti=0;iSystem.out.println(preStr+childs[i].getName());
if(childs[i].isDirectory()){
tree(childs[i],level+1);
}
}
}
}
publicclassTestEnum{
publicenumMyColor{red,green,blue};
publicenumMyDoorOpener{me,mywife};
publicstaticvoidmain(String[]args){
MyColorm=MyColor.red;
switch(m){
casered:
System.out.println("red");
break;
casegreen:
System.out.println("green");
break;
default:
System.out.println("default");
}
System.out.println(m);
}
}