1.先取得第i个字符:
int i=3;
String str="abcdefg";
char temp=str.charAt(i);
2.在利用char的wrapper类Character的工具;
str=str.substring(0,i)+Character.toUpperCase(temp)
+str.substring(i+1,str.length());
system.out.println("The new string is "+str);
int i=3;
String str="abcdefg";
char temp=str.charAt(i);
2.在利用char的wrapper类Character的工具;
str=str.substring(0,i)+Character.toUpperCase(temp)
+str.substring(i+1,str.length());
system.out.println("The new string is "+str);
{
public static void main(String[] args)
{
String s1 = "abcdefg";
String num = JOptionPane.showInputDialog("Which characters do you want to change?");
int i = Integer.parseInt(num)-1;
String temp1 = s1.substring(i,i+1);
String temp2 =temp1.toUpperCase();
String temp3 = s1.substring(0,i);
String temp4 = s1.substring(i+1);
String newstring = temp3+temp2+temp4;
System.out.println(newstring); System.exit(0);
}
}我也是新手,写的不好,多包涵!
String ch= str.subString(i,i+1);
ch.toUpperCase();
StringBuffer sb=new StringBuffer(str);
sb.setCharAt(i,ch.charAt(0));
str=sb.toString();
StringBuffer sb=new StringBuffer(str);
sb.setCharAt(i,Character.toUpperCase(str.charAt(i)));
str=sb.toString();