在if語句中運行

首先，我對Java很新穎（大概一個星期），我對某些東西有點困惑，基本上我試着看看一個布爾值是否等於真，則啓動一個線程，所以這裏是我的代碼（順便說一句，我用兩個班）在if語句中運行

package apackage; 
import java.util.Scanner; 

public class Threads2 { 

    public static void main(String args[]){ 

     Scanner scanner = new Scanner(System.in); 
     String selection; 
     System.out.println("Input one of the following answers for which timer you would like to start:"); 
     System.out.println("Dragon, Baron, RedBuffNeutral, BlueBuffNeutral, RedBuffEnemy & BlueBuffEnemy"); 

     selection = scanner.next(); 
     if (selection.equalsIgnoreCase("dragon")){ 
      boolean dragon = true; 
      Thread t1 = new Thread(new Threads("Dragon", "THREAD1")); 
      t1.start(); 
     }else if (selection.equalsIgnoreCase("baron")){ 
      Thread t2 = new Thread(new Threads("Baron", "THREAD2")); 
      t2.start(); 
     }else if (selection.equalsIgnoreCase("redbuffneutral")){ 
      Thread t3 = new Thread(new Threads("Red Buff Neutral", "THREAD3")); 
      t3.start(); 
     }else if (selection.equalsIgnoreCase("bluebuffneutral")){ 
      Thread t4 = new Thread(new Threads("Blue Buff Neutral", "THREAD4")); 
      t4.start(); 
     }else if (selection.equalsIgnoreCase("redbuffenemy")){ 
      Thread t5 = new Thread(new Threads("Red Buff Enemy", "THREAD5")); 
      t5.start(); 
     }else if (selection.equalsIgnoreCase("bluebuffenemy")){ 
      Thread t6 = new Thread(new Threads("Blue Buff Enemy", "THREAD6")); 
      t6.start(); 
     }else{ 
      System.out.println("You inputted an incorrect answer, please choose from the following next time:"); 
      System.out.println("Dragon, Baron, RedBuffNeutral, BlueBuffNeutral, RedBuffEnemy & BlueBuffEnemy"); 
     } 
    } 
}

和

package apackage; 
import java.util.Random; 

public class Threads implements Runnable{ 
    String name; 
    String text; 
    int time = 999; 
    int RedBuffNeutral, BlueBuffNeutral, RedBuffEnemy, BlueBuffEnemy = 300000; 
    int Dragon = 360000; 
    int Baron = 420000; 
    Random r = new Random(); 

    public Threads(String x, String z){ 
     text = z; 
     name = x; 
    } 

    if (dragon = true) 
     public void run(){ 

      try{ 
       System.out.printf("%s is dead for %d\n", name, Dragon); 
       Thread.sleep(Dragon); 
       System.out.printf("%s has respawned!\n", name); 
      }catch(InterruptedException exception){ 
       System.out.printf("An error has occured in %s", name); 
      } 
     } 
    } 
}

我有一流的沒有問題，這是當它實際上涉及到運行線程是當我遇到問題的時候，我真的不知道該怎麼做，並且錯誤發生在第二課的第16行，它說s：令牌「if」的語法錯誤，無效AnnotationName 任何幫助將不勝感激，如果您想了解我的問題的更多信息只需要問！謝謝：d

來源

2014-09-23 user3910313

'如果dragon = true'，這是一個任務，而不是條件 – Coffee 2014-09-23 17:13:27

有問題的if語句似乎也超出了類中任何方法的範圍。 – user3062946 2014-09-23 17:15:24

我看不到'龍'是在哪裏申明的，我想可能還有其他的bug – Coffee 2014-09-23 17:15:49

這裏有一個semantic error：

if (dragon = true) 
    public void run(){ /* etc */

你的意思不是說你想在這裏：你是龍VAR分配真實的，之後是總是如此。

您必須使用

if (dragon == true)

來源

2014-09-23 17:13:49 Coffee

一個錯誤是你使用=賦值運算符來測試平等。相反，請使用==運算符。

if (dragon == true)

但是，你得到同樣的結果，如果你簡單地測試了布爾值本身：

if (dragon)

來源

2014-09-23 17:14:00

=是賦值運算符。等於運算符是==，所以，你的代碼應該閱讀：

if (dragon == true)

更妙的是，因爲dragon是boolean，它可以直接評價：

if (dragon)

來源

2014-09-23 17:14:37 Mureinik

非常感謝您的幫助，所以我嘗試了這一點，但它仍然得到相同的錯誤！有任何想法嗎？ – user3910313 2014-09-25 16:17:06

我編輯您的文章，可讀性更強。請注意else-if語句，它使您不必縮減代碼太多並使其更具可讀性。

但是，您在您的線程類中調用該類中不存在的變量。你的if語句也應該有@AndyThomas提到的格式，但你也可以不具有if語句。它需要位於方法或構造函數內。它應該是這個樣子：

package apackage; 
import java.util.Scanner; 

public class Threads2 { 

    public static void main(String args[]){ 

     Scanner scanner = new Scanner(System.in); 
     String selection; 
     System.out.println("Input one of the following answers for which timer you would like to start:"); 
     System.out.println("Dragon, Baron, RedBuffNeutral, BlueBuffNeutral, RedBuffEnemy & BlueBuffEnemy"); 

     boolean dragon = false; 
     selection = scanner.next(); 
     if (selection.equalsIgnoreCase("dragon")){ 
      dragon = true; 
      new Threads(dragon, "Dragon", "THREAD1"); 
     }else if (selection.equalsIgnoreCase("baron")){ 
      new Threads(dragon, "Baron", "THREAD2"); 
     }else if (selection.equalsIgnoreCase("redbuffneutral")){ 
      new Threads(dragon, "Red Buff Neutral", "THREAD3"); 
     }else if (selection.equalsIgnoreCase("bluebuffneutral")){ 
      new Threads(dragon, "Blue Buff Neutral", "THREAD4"); 
     }else if (selection.equalsIgnoreCase("redbuffenemy")){ 
      new Threads(dragon, "Red Buff Enemy", "THREAD5"); 
     }else if (selection.equalsIgnoreCase("bluebuffenemy")){ 
      new Threads(dragon, "Blue Buff Enemy", "THREAD6"); 
     }else{ 
      System.out.println("You inputted an incorrect answer, please choose from the following next time:"); 
      System.out.println("Dragon, Baron, RedBuffNeutral, BlueBuffNeutral, RedBuffEnemy & BlueBuffEnemy"); 
     } 
    } 
}

和

package apackage; 
import java.util.Random; 

public class Threads implements Runnable{ 

    String name; 
    String text; 
    int time = 999; 
    int RedBuffNeutral, BlueBuffNeutral, RedBuffEnemy, BlueBuffEnemy = 300000; 
    int Dragon = 360000; 
    int Baron = 420000; 
    Random r = new Random(); 

    public Threads(boolean dragon, String x, String z){ 
     text = z; 
     name = x; 
     if (dragon == true) { 
      run(); 
     } 
    } 

    @Override 
    public void run(){ 
     try{ 
      System.out.printf("%s is dead for %d\n", name, Dragon); 
      Thread.sleep(Dragon); 
      System.out.printf("%s has respawned!\n", name); 
     }catch(InterruptedException exception){ 
      System.out.printf("An error has occured in %s", name); 
     } 
    } 
}

我還沒有試過這種代碼，但它更有意義。讓我知道如何去:)

來源

2014-09-23 17:29:21 TheShahin

通過你的原代碼，我想如果條件應該是

if(Dragon == 360000){

如果你真的希望它是一個布爾值，這將是一個更好的辦法將其命名爲「isDragon 「把它放在如果條件。

還有一件事情，按照Java命名規則，你應該用第一個字符命名的局部變量被小寫。

來源

2014-09-23 18:20:03 Javakid

在if語句中運行

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