Java - 空指針異常，但我可以得到值

Question

所以我寫了一個程序，並有3個NPEs - 我不明白爲什麼，也許我是我的流感失明;）有人可以告訴我什麼是錯的？

我不粘貼整個代碼，但只有重要的類。剩下的就好了。

package maszyna; 
import java.util.*; 

public class Main { 


public static void main(String[] args) { 

    User user = new User(); // first NPE 
    Mode.start = true; 
    Mode.pause = false; 

    Machine machine = new Machine(); 
    user.addListener(machine);  


    user.setTimeStart("1:15:30"); 
    //System.out.println("It's " +user.getTimeStart()); // but I can see this 
    user.setTimePause("1:15:40");//when it's uncommented ofc 
    user.setTimeResume("1:15:50"); 
    user.setTimeRestart("1:16:00"); 
    user.setTimeStop("1:16:10"); 



} 
} 

而這裏的類用戶：

package maszyna; 
import static java.lang.Thread.sleep; 
import java.util.*; 



public class User{ 

    String name; 
    String timeStart; 
    String timeStop; 
    String timePause; 
    String timeResume; 
    String timeRestart; 
    String[] temp = new String[3];  
    int[] SMTi = new int[3]; 
    private List<UserListener> listeners; 

      Thread life = new Thread(){ 
      @Override 
    public void run() 
    { 
     while(Mode.start==true){ 

         Calendar cal = Calendar.getInstance();  
         int hour = cal.get(Calendar.HOUR_OF_DAY); 
         int minute = cal.get(Calendar.MINUTE); 
         int second = cal.get(Calendar.SECOND); 

      machineStart(hour, minute, second); 
      machineStop(hour, minute, second); 
      machinePause(hour, minute, second); 
          machineResume(hour, minute, second); 
          machineRestart(hour, minute, second); 

      try { 
       sleep(200); 
      } catch (InterruptedException e) { 
       e.printStackTrace(); 
      } 
     } 
    } 

}; 

    public User(){  
     this.listeners = new ArrayList<UserListener>(); 
    life.start(); 
    } 



public String getTimeStart() { 
    return timeStart; 
} 

public void setTimeStart(String timeStart) { 
    this.timeStart = timeStart; 
} 

public String getTimeStop() { 
    return timeStop; 
} 

public void setTimeStop(String timeStop) { 
    this.timeStop = timeStop; 
} 

public String getTimePause() { 
    return timePause; 
} 

public void setTimePause(String timePause) { 
    this.timePause = timePause; 
} 

public String getTimeResume() { 
    return timeResume; 
} 

public void setTimeResume(String timeResume) { 
    this.timeResume = timeResume; 
} 

public String getTimeRestart() { 
    return timeRestart; 
} 

public void setTimeRestart(String timeRestart) { 
    this.timeRestart = timeRestart; 
} 

    int[] tStart = splitMyTime(getTimeStart()); //they are set, aren't they? 
    int[] tPause = splitMyTime(getTimePause()); //I can get them in Main when I want to 
    int[] tResume = splitMyTime(getTimeResume()); 
    int[] tRestart = splitMyTime(getTimeRestart()); 
    int[] tStop = splitMyTime(getTimeStop()); 



public int[] splitMyTime(String cos){ 

    if(cos==null){ //I made this if for tests 
     System.out.println("OMG, it's null"); //it displays OMG 5 times 
     int[] kot = {1, 2, 3};//and part below throws NPE, when if is hidden in comment 
     Mode.start = false; 
     return kot; 
    } 
    else{ // and this part causes NPE 
    temp = cos.split(":|.");  
int l = temp.length;  
for(int a=0; a<l; a++){ 
SMTi[a] = Integer.parseInt(temp[a]); //NPE, when I just write the arguments above instead getters 
    } 

return SMTi; 
    } 
} 



public synchronized void addListener(UserListener listener) 
{ 
    listeners.add(listener); 
} 

public synchronized void removeListener(UserListener listener) 
{ 
    listeners.remove(listener); 
} 


protected synchronized void machineStart(int hour, int minute, int second) 
{     

      if(second == tStart[2] && 
        minute == tStart[1] && 
        hour == tStart[0]){ 


    System.out.println("START \n \n");   


    UserEvent ue = new UserEvent(this); 

    for(UserListener ul: listeners) 
    { 
     ul.machineStart(ue); 
    } 
      } 
} 


    protected synchronized void machineStop(int hour, int minute, int second) 
{    
      if(second == tStop[2] && 
        minute == tStop[1] && 
        hour == tStop[0]){ 
    System.out.println("STOP \n \n"); 
    UserEvent ue = new UserEvent(this); 
    for(UserListener ul: listeners) 
    { 
     ul.machineStop(ue); 
    } 
      } 
} 


    protected synchronized void machinePause(int hour, int minute, int second) 
{ 
      if(second == tPause[2] && 
        minute == tPause[1] && 
        hour == tPause[0]){ 
    System.out.println("PAUSE \n \n"); 
      Mode.pause = true; 
    UserEvent ue = new UserEvent(this); 
    for(UserListener ul: listeners) 
    { 
     ul.machinePause(ue); 
    } 
      } 
} 


    protected synchronized void machineResume(int hour, int minute, int second) 
{ 
      if(second == tResume[2] && 
        minute == tResume[1] && 
        hour == tResume[0]){ 
    System.out.println("RESUME \n \n"); 
      Mode.pause = false; 
    UserEvent ue = new UserEvent(this); 
    for(UserListener ul: listeners) 
    { 
     ul.machineResume(ue); 
    } 
      } 
} 


    protected synchronized void machineRestart(int hour, int minute, int second) 
{ 
     if(second == tRestart[2] && 
        minute == tRestart[1] && 
        hour == tRestart[0]){ 
    System.out.println("RESTART \n \n"); 
    UserEvent ue = new UserEvent(this); 
    for(UserListener ul: listeners) 
    { 
     ul.machineRestart(ue); 
    } 
     } 
} 


} 

我試圖重新組織代碼的部分，但它並沒有幫助。我不知道發生了什麼事。我需要外面的人來看看這個新鮮事物。非常感謝。

您想堆棧跟蹤，這是:)

run: 
Exception in thread "main" java.lang.NullPointerException 
at maszyna.User.splitMyTime(User.java:110) 
at maszyna.User.<init>(User.java:93) 
at maszyna.Main.main(Main.java:9) 
Java Result: 1 
BUILD SUCCESSFUL (total time: 1 second) 

Answer 1

根據您的堆棧跟蹤，你可以做下列步驟操作：

A）更改屬性初始化是這樣的：

int[] tStart = null; 
int[] tPause = null; 
int[] tResume = null; 
int[] tRestart = null; 
int[] tStop = null; 

B）添加劃分時間的方法：

public void splitAllTimes() { 
    this.tStart = splitMyTime(getTimeStart()); 
    this.tPause = splitMyTime(getTimePause()); 
    this.tResume = splitMyTime(getTimeResume()); 
    this.tRestart = splitMyTime(getTimeRestart()); 
    this.tStop = splitMyTime(getTimeStop()); 
} 

C）更改您的主要方法：

public static void main(String[] args) { 

    User user = new User(); 
    Mode.start = true; 
    Mode.pause = false; 

    Machine machine = new Machine(); 
    user.addListener(machine);  


    user.setTimeStart("1:15:30"); 
    user.setTimePause("1:15:40"); 
    user.setTimeResume("1:15:50"); 
    user.setTimeRestart("1:16:00"); 
    user.setTimeStop("1:16:10"); 
    //------------------Add this line-------------------- 
    user.splitAllTimes(); //Add this line to init your attrbutes 
}