String(字符串)的练习

package com.qf.test;

import com.qf.home.Goods;

public class Test {

public static void main(String[] args) {

String s="akslskskskssk";

fun1(s);

fun12(s);

fanzhaun(s);

fanzhuan2(s);

fun3();

fun4();

fun41();

}

String s="how do you do",写一个方法使用此字串最后得到s1="od uoy od nowoh";

//先反转在插入

public static void fun4() {

String s="how do you do";

StringBuilder sBuilder=new StringBuilder(s);

sBuilder.reverse();//反转方法

sBuilder.insert(sBuilder.indexOf("woh"), "no");//插入"no"字符串

System.out.println(sBuilder);

}

//先插入再反转

public static void fun41() {

String s="how do you do";

StringBuilder sBuilder=new StringBuilder(s);

sBuilder.insert(sBuilder.indexOf(" "), "on");

sBuilder.reverse();

System.out.println(sBuilder);

}

//String s="go home go home go home";使用StringBuilder在每一个go的后面添加一个" my";

//indexOf insert

public static void fun3() {

String s="go home go home go home";

StringBuilder sBuilder=new StringBuilder(s);

int index=0;

int count=1;

while(index!=-1) {

index = sBuilder.indexOf("go", index);

if(index!=-1) {

sBuilder.insert(index+2, " my");

index+=5*count;

count++;

}

}

System.out.println(sBuilder);

}

//写一个方法，传入一个String，将String反转，不能使用reverse

//用第三个变量来交换

public static void fanzhaun(String string) {

char[] charArray = string.toCharArray();

for (int i = 0; i < charArray.length/2; i++) {

char c=charArray[i];

charArray[i]=charArray[charArray.length-1-i];

charArray[charArray.length-1-i]=c;

}

System.out.println(new String(charArray));

}

//两个数组 后一个数组的第一个存放前一个数组的最后一个 循环

public static void fanzhuan2(String string) {

char[] charArray = string.toCharArray();

char[] cs=new char[charArray.length];

for (int i = 0; i < charArray.length; i++) {

cs[i]=charArray[charArray.length-1-i];

}

System.out.println(new String(cs));

}

//String s="akslskskskssk",使用方法来获取k出现的次数，以及每一次出现的具体位置

//toCharArray() indexOf()

public static void fun12(String string) {

char[] charArray = string.toCharArray();

int count=0;

int index=0;

while (index!=-1) {

index= string.indexOf('k', index);

if(index!=-1) {

count++;

System.out.println("第"+count+"出现的位置===="+index);

index++;

}

}

System.out.println("出现的次数:"+count);

}

public static void fun1(String string) {

char[] charArray = string.toCharArray();

int count=0;

for (int i = 0; i < charArray.length; i++) {

if (charArray[i]=='k') {

count++;

System.out.println("第"+count+"出现的位置"+i);

}

}

System.out.println("出现的次数:"+count);

}

}