我把錯誤放到了代碼的註釋中。
String t;
int l = t.length();
char[] a;
a = new char[l];
String rel = ",";
String ret = null; //you initialize ret to null, it should be "";
for (int i = 0; i<l; i++){
//you always set it to the character at position 0, you should do t.charAt(i)
//you don't need to use the wrapper class just t.charAt(i) will be fine.
a[i] = new Character(t.charAt(0));
}
for (int v = 0; v<l; v--){//you decrement v instead of incrementing it, this will lead to exceptions
ret += a[v];
ret += rel;//you always add the delimiter, note that this will lead to a trailing delimiter at the end
}
你可能想嘗試一個StringBuilder。這比使用字符串連接更有效率。使用數組a也不是必須的。看看這個實現。
String t = "Test";
StringBuilder builder = new StringBuilder();
if(t.length() > 0){
builder.append(t.charAt(0));
for(int i=1;i<t.length();i++){
builder.append(",");
builder.append(t.charAt(i));
}
}
System.out.println(builder.toString());
使用'StringBuilder'。 –