沒有看到來自Java的完整堆棧跟蹤錯誤

Question

背景：我正在爲我的一個大學課程及其相當大的項目製作模擬器。

問題：但是，每當I型「I」或「c」（在代碼示出的細節）我從一個的java.lang ArrayIndexOutOfBoundsException異常異常（未定製的處理程序）沒有任何堆棧跟蹤，並因此我找不到問題。

照片：​​

代碼：

/** 
* Creates world and starts loop of commands 
*/ 
public void run() { 
    if(configFile == null) {System.exit(0);} 
    initWorld(); 
    if(world == null) { 
     System.out.println("Unable to read config file."); 
     return; 
    } 
    world.print(); 

    Scanner reader = new Scanner(System.in); 
    String line = reader.nextLine(); 
    while(canRun()) { 
     if(line.equals("p")) { 
      world.print(); 
     } else if(line.equals("c")) { 
      world.turn(); 
      Species.printInfo(); 
      steps++; 
      if(steps % 50 == 0) { 
       Species.printSummary(50); 
      } 
     } else if(line.equals("r")) { 
      Species.printStatus(); 
     } 

     if(line.equals("i")) { 
      world.turn(); 
      steps++; 
      if(steps % 50 == 0) { 
       Species.printSummary(50); 
      } 
     } else { 
      line = reader.nextLine(); 
     } 
    } 
    world.print(); 
    Species.printSummary(-1); 
    if(this.steps >= this.maxSteps) 
     System.out.println("Simulation ended because the turn limit was reached."); 
    else if(getPopulationOfWorld() == 0) 
     System.out.println("Simulation ended because all of the species died."); 
    else if(getChangesInPastSteps() == 0) 
     System.out.println("Simulation ended because there were no changes in the last 50 turns."); 
} 


    public void turn() { 
    int curSteps = this.getSteps(); 
    System.out.println("Current Steps: " + curSteps); 

    if(Species.getDeaths().size() == curSteps) { 
     Species.getDeaths().add(new ArrayList<Integer>()); 
     for(int i = 0; i < Species.getSpecies().size(); i++) { 
      Species.getDeaths().get(curSteps).add(0); 
     } 
    } 
    if(Species.getBirths().size() == curSteps) { 
     Species.getBirths().add(new ArrayList<Integer>()); 
     for(int i = 0; i < Species.getSpecies().size(); i++) { 
      Species.getBirths().get(curSteps).add(0); 
     } 
    } 

    System.out.println("Begin Turning!"); 
    for(int i = 0; i < board.size(); i++) { 
     List<Cell> row = board.get(i); 
     for(int j = 0; j < row.size(); j++) { 
      Cell cell = row.get(j); 
      if(cell.getAnimal() != null) { 
       cell.getAnimal().activity(); 
      } 
      if(cell.getPlant() != null) { 
       cell.getPlant().activity(); 
      } 
     } 
    } 
    steps++; 
} 

Answer 1

嘗試使用嘗試捕捉

public void run() { 
if(configFile == null) {System.exit(0);} 
initWorld(); 
if(world == null) { 
    System.out.println("Unable to read config file."); 
    return; 
} 
world.print(); 

Scanner reader = new Scanner(System.in); 
String line = reader.nextLine(); 
while(canRun()) { 
try { 
    if(line.equals("p")) { 
     world.print(); 
    } else if(line.equals("c")) { 
     world.turn(); 
     Species.printInfo(); 
     steps++; 
     if(steps % 50 == 0) { 
      Species.printSummary(50); 
     } 
    } else if(line.equals("r")) { 
     Species.printStatus(); 
    } 

    if(line.equals("i")) { 
     world.turn(); 
     steps++; 
     if(steps % 50 == 0) { 
      Species.printSummary(50); 
     } 
    } else { 
     line = reader.nextLine(); 
    } 
} 
catch(Exception e) { 
    e.printStackTrace(); // or do print full stack trace on log file 
} 
} 
world.print(); 
Species.printSummary(-1); 
if(this.steps >= this.maxSteps) 
    System.out.println("Simulation ended because the turn limit was reached."); 
else if(getPopulationOfWorld() == 0) 
    System.out.println("Simulation ended because all of the species died."); 
else if(getChangesInPastSteps() == 0) 
    System.out.println("Simulation ended because there were no changes in the last 50 turns."); 

}

Answer 2

1. 請張貼整個工作的例子。此示例缺少複製問題所需的一半代碼。

2. 一般來說，你應該使用Java的內置迭代器只要有可能，即

不要做：

for(int i = 0; i < board.size(); i++) { 
    List<Cell> row = board.get(i); 
... 
} 

相反，這樣做：

for(List<Cell> row : board){ 
... 
} 

正如其中一條評論所述，您應該使用Eclipse調試器針對這種情況。

我不確定您的canRun()方法中有什麼，但您應該在讀取它之前獲得checking whether your scanner has a next line。