為啥我做的練習不出結果呢？
可能有的東西學了忘了，導致我找不出問題所在，請大家指教????~~
public void testSort3(){
List<String> stringList2=new ArrayList<String>();
String str="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
? ?for(int j=0;j<10;j++){
? ? Random random=new Random();
? ? int a=random.nextInt(11);
? ?StringBuilder str1=new StringBuilder();
? ?for(int i=0;i<a;i++){
? ? int b=random.nextInt(str.length()+1);
? ? str1.append(str.substring(b, b));
? ?}
? ?String str2=str1.toString();
stringList2.add(str2);
? ?}
? ?for (String string : stringList2) {
System.out.println(string);
}
}
2016-07-29
import?java.awt.List; import?java.util.ArrayList; import?java.util.Random; public?class?testSort3{ public?static?void?main(String?args[]){ ArrayList<String>?stringList2=new?ArrayList<String>(); String?str="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; ???for(int?j=0;j<10;j++){ ??? Random?random=new?Random(); ??? int?a=random.nextInt(11); ???StringBuilder?str1=new?StringBuilder(); ???for(int?i=0;i<a;i++){ ??? int?b=random.nextInt(str.length()+1); ??? str1.append(str.substring(b,?b)); ???} ???String?str2=str1.toString(); stringList2.add(str2); ???} ???for?(String?string?:?stringList2)?{ System.out.println(string); } }你格式寫的就不對，像我這樣改
2016-10-30
public void testSort3(){
List<String> stringList = new ArrayList();
Random random = new Random();
String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
// System.out.println(str);
for (int i = 0; i < 10; i++) {
int length = random.nextInt(11);
StringBuilder str1 = new StringBuilder();
for (int j = 0; j < length; j++) {
int ?b = random.nextInt(str.length()-1);
str1.append(str.substring(b, b+1));
}
String str2 = str1.toString();
// System.out.println(str2);
stringList.add(str2);
}
System.out.println("----------排序前------------");
for(String string : stringList){
System.out.println(string);
}
Collections.sort(stringList);
System.out.println("----------排序后-------------");
for(String string : stringList){
System.out.println(string);
}
}
2016-07-30
應該是
str.length()-1;
str.subtring(b,b+1);