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Question

簡化實施Collections.sort我需要梳理工作的名單，我現在做的：

List<Job> jobs = new ArrayList<Job>(); 
Job job0 = new Job("a", 1, Arrays.asList("t0")); 
Job job1 = new Job("a", 2, Arrays.asList("t0")); 
jobs.add(job0); 
jobs.add(job1); 
Comparator<Job> comparator = new Comparator<Job>() { 
    @Override 
    public int compare(Job o1, Job o2) { 
    if (o1.getOrder() > o2.getOrder()) { 
     return 1; 
    } 
    return 0; 
    } 
}; 
Collections.sort(jobs, comparator); 

其中：

public class Job { 
    private String path; 
    private List<String> targets; 
    private final int order; 
    public Job(String path, int order, List<String> targets) { 
    this.path = path; 
    this.order = order; 
    this.targets = targets; 
    } 
... 
    public int getOrder() { 
    return order; 
    } 
} 

我想對此進行簡化。所以，我曾嘗試：

public class Job implements Comparable<Integer> { 
    private String path; 
    private List<String> targets; 
    private final int order; 
    public Job(String path, int order, List<String> targets) { 
    this.path = path; 
    this.order = order; 
    this.targets = targets; 
    } 
    public int compareTo(Integer o) { 
    // TODO Auto-generated method stub 
    return 0; 
    } 
} 

和

List<Job> jobs = new ArrayList<Job>(); 
Collections.sort(jobs); 

但得到：

Bound mismatch: The generic method sort(List<T>) of type Collections is not applicable for the arguments (List<Job>). The inferred type Job is not a valid substitute for the bounded parameter <T extends Comparable<? super T>> 

是否有可能避免將一個比較？

Answer 1

你可以做這樣的：

public class Job implements Comparable<Job> { // a job is comparable to another job 
    private String path; 
    private List<String> targets; 
    private final int order; 
    public Job(String path, int order, List<String> targets) { 
    this.path = path; 
    this.order = order; 
    this.targets = targets; 
    } 
    public int compareTo(Job j) { 
    return this.order - j.order; // here you specify how you want your jobs sorted 
    } 
}