java how to add characters to a string code example

Example 1: add one character to string java

char ch='A';
String str="pple";
str= ch+str;   // str will change to "Apple"

Example 2: insert string in string java

String newString = originalString.substring(0, index + 1) 
                           + stringToBeInserted 
                           + originalString.substring(index + 1);