public class Test {
  public static void stringReplace(String input) {  input = input.replace('j', 'c');
 }
 public static void stringBufferReplace(StringBuffer input) {
   input = input.append("c"); }
 public static void main(String args[]) {
  String testString = "java";
   StringBuffer testStringBuffer = new StringBuffer("java");
   stringReplace(testString);
   stringBufferReplace(testStringBuffer);
   // testString=testString.replace('j', 'c');//得要这样
   System.out.println(testString + testStringBuffer); }
}