的Java自動遞增ID

Question

我做一些編碼在Java中，但它不工作：

public class job 
{ 
    private static int count = 0; 
    private int jobID; 
    private String name; 
    private boolean isFilled; 

    public Job(, String title,){ 
     name = title; 
     isFilled = false; 
     jobID = ++count; 
    } 
} 

我需要自動遞增時，將創建一個新的項目內的ID。

Answer 1

試試這個：

public class Job { 
    private static final AtomicInteger count = new AtomicInteger(0); 
    private final int jobID; 
    private final String name; 

    private boolean isFilled; 

    public Job(String title){ 
    name = title; 
    isFilled = false; 
    jobID = count.incrementAndGet(); 
} 

Answer 2

public class job 
{ 
    private static int jobID; 
    private String name; 
    private boolean isFilled; 

    public Job(String title){ 
     name = title; 
     isFilled = false; 

     synchronized { 
      jobID = jobID + 1; 
     } 
} 

Answer 3

public class Job // Changed the classname to Job. Classes a written in CamelCasse Uppercase first in Java codeconvention 
{ 
    private static int count = 0; 
    private int jobID; 
    private String name; 

    private boolean isFilled; // boolean defaults to false 

    public Job(String title){ // Your code wan unable to compile here because of the ',' 
     name = title; 
     isFilled = false;  // sets false to false 
     jobID = ++count; 
    } 
} 

您的代碼將工作，但你可能會得到一些問題，如果你打Integer.MAX_VALUE。

這可能是一個更好的選擇long。或者，如果你只需要一個唯一的標識符UUID.randomUUID()

Answer 4

使用下，

public class TestIncrement { 
private static int count = 0; 
private int jobID; 
private String name; 

private boolean isFilled; 

public TestIncrement(String title) { 
    name = title; 

    isFilled = false; 
    setJobID(++count); 
} 

public int getJobID() { 
    return jobID; 
} 

public void setJobID(int jobID) { 
    this.jobID = jobID; 
} 

}

請使用下列測試此

public class Testing { 

/** 
* @param args 
*/ 
public static void main(String[] args) { 
    // TODO Auto-generated method stub 

    for (int i = 0; i < 10; i++) { 
     TestIncrement tst = new TestIncrement("a"); 
     System.out.println(tst.getJobID()); 
    } 
} 

}