Syntax error on token “;”, { expected after this token in Random string creator

问题

I am writing code to generate a random 3 letter strings using the letters a, b, and c. I am getting the error message "Syntax error on token ";", { expected after this token" after the line where i create the random variable (Random rand = new Random();). I do not know why I am getting this error when it looks fine to me.

I am also getting the error message: Syntax error, insert "}" to complete ClassBody, after the last bracket in the program. I am almost postive all my closing brackets match up so I do not know where this error is coming from. PLEASE HELP!!

 import java.util.*;


 public class Orders {

String alphabet = "abc";
ArrayList<String> list = new ArrayList<String>();
int n = alphabet.length();

Random rand = new Random();
for (int i = 0; i < 10000; i++){
    char a = alphabet.charAt(rand.nextInt(n));
    char b = alphabet.charAt(rand.nextInt(n));
    char c = alphabet.charAt(rand.nextInt(n));

    String s = Character.toString(a) + Character.toString(b) + Character.toString(c); 

    if(list.indexOf(s) == -1){
        list.add(s);
    }
}
 system.out.println(arrayList);
}

回答1:

In Java, you cannot directly write the executable statements in class. You need to move your code in a method. Only variables declaration is allowed outside the method/blocks. Just for the sake of testing, ,move everthing to main method. Try this:

  public class Orders {

        public static void main(String argsp[]) {
            String alphabet = "abc";
            ArrayList<String> list = new ArrayList<String>();
            int n = alphabet.length();

            Random rand = new Random();
            for (int i = 0; i < 10000; i++){
               char a = alphabet.charAt(rand.nextInt(n));
               char b = alphabet.charAt(rand.nextInt(n));
               char c = alphabet.charAt(rand.nextInt(n));

               String s = Character.toString(a) + Character.toString(b) + Character.toString(c); 

               if(list.indexOf(s) == -1){
                   list.add(s);
               }
            }
            System.out.println(list);
        }

}

Note: system.out.println(arrayList); will throw an error because there is no varaible called arrayList, i think it should be replaced with variable list. Also system should be System.

回答2:

In java you can't simply code loops and other actions as part of the class definition, but rather as method/constructor/block definitions inside the class

for (int i = 0; i < 10000; i++){
    char a = alphabet.charAt(rand.nextInt(n));
    char b = alphabet.charAt(rand.nextInt(n));
    char c = alphabet.charAt(rand.nextInt(n));

    String s = Character.toString(a) + Character.toString(b) + Character.toString(c); 

    if(list.indexOf(s) == -1){
        list.add(s);
    }
}
 system.out.println(arrayList);

So this code should be in method/constructor/block.
For example in method

public void printList(){
 for (int i = 0; i < 10000; i++){
        char a = alphabet.charAt(rand.nextInt(n));
        char b = alphabet.charAt(rand.nextInt(n));
        char c = alphabet.charAt(rand.nextInt(n));

        String s = Character.toString(a) + Character.toString(b) + Character.toString(c); 

        if(list.indexOf(s) == -1){
            list.add(s);
        }
    }
     system.out.println(arrayList);  
}

Please refer this link for more details.

回答3:

You just need to write your code inside the main function.
You just miss the main function.

Your code

import java.util.*;
 public class Orders {//Include main function

 String alphabet = "abc";
ArrayList<String> list = new ArrayList<String>();
int n = alphabet.length();

Random rand = new Random();
for (int i = 0; i < 10000; i++){
    char a = alphabet.charAt(rand.nextInt(n));
    char b = alphabet.charAt(rand.nextInt(n));
    char c = alphabet.charAt(rand.nextInt(n));

    String s = Character.toString(a) + Character.toString(b) + Character.toString(c); 

    if(list.indexOf(s) == -1){
        list.add(s);
    }
}
 system.out.println(arrayList);
}

Correct code

package testprob;
import java.util.*;
public class testprob {
public static void main(String arrg[]) {//you need to add main function 
     String alphabet = "abc";
     ArrayList<String> list = new ArrayList<String>();
     int n = alphabet.length();

     Random rand = new Random();
     for (int i = 0; i < 10000; i++){
         char a = alphabet.charAt(rand.nextInt(n));
         char b = alphabet.charAt(rand.nextInt(n));
         char c = alphabet.charAt(rand.nextInt(n));

         String s = Character.toString(a) + Character.toString(b) + Character.toString(c); 

         if(list.indexOf(s) == -1){
             list.add(s);
         }
     }
      System.out.println(list);

}

}

回答4:

I was getting a error "invalid token 'manage()..." when i coded as below .That is when i wrote my code directly to a class.

//before

public class test{ WebDriver driver=new FirefoxDriver(); driver.manage().timeouts().pageLoadTimeout(30, TimeUnit.SECONDS); driver.get("http://http://www.extjs-tutorial.com/live-examples/extjs4/CRUD-in-Form-model/default.htm"); }'

After i moved my code to a method , it worked

//after

 public class test{
    public void setup(){
    WebDriver driver=new FirefoxDriver();
    driver.manage().timeouts().pageLoadTimeout(30, TimeUnit.SECONDS);
    driver.get("http://http://www.extjs-tutorial.com/live-examples/extjs4/CRUD-in-Form-model/default.htm");
    }}

回答5:

The reason you get a syntax error in that code is that you have an extra bracket. to the code above the error!

来源：https://stackoverflow.com/questions/18836404/syntax-error-on-token-expected-after-this-token-in-random-string-creator

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java

syntax

syntax-error

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