用JAVA编程求字符a在字符串str="abcda va"中出现的位置和次数

Question

要求用到indexof()!

Answer 1

String str="abafsdasdsdaaaa";
String[] arr = new String[str.length()];
int cishu = 0;
int jilv = 0;
for(int i = 0; i < str.length(); i++){
arr[i] = str.substring(i, i+1);
if(arr[i].equals("a")){
++cishu;
System.out.println("第" + ++jilv + "个" + arr[i] + "出现的位置是：" + i);
}
}
System.out.println("一共出现了："+ cishu +"次!");
}