用JAVA如何将两个汉字替换

class HanZi
{
String str;
HanZi(String s)
{
str = s;
}
public void reverse(HanZi hz)
{
String tamp;
tamp = hz.str;
hz.str = str;
str = tamp;
}
}

public class Test
{
public static void main(String[] args)
{
HanZi a = new HanZi("日");
HanZi b = new HanZi("月");
System.out.println(a.str);
System.out.println(b.str);
a.reverse(b);
System.out.println(a.str);
System.out.println(b.str);
}
}

public String replace(String value,char a,char b){
char[] cs=value.toCharArray();
for(int i=0;i<cs.length;i++){
if(cs[i]==a){
cs[i]=b;
}else if(cs[i]==b){
cs[i]=a;
}
}
return new String(cs);
}
以上方法仅用于单个字的替换，如果用于字符串替换的话需要用indexOf方法去遍历整个字符串了。