的Java：ArrayList中我如何才能

-1

public class Media { 
double supporto; 
double i_m; 
String idSentence; 

public Media(double supporto,double i_m,String idSent){ 
    this.supporto=supporto; 
    this.i_m=i_m; 
    this.idSentence=idSent; 
} 


public double getSupporto(){ 
    return this.supporto; 
} 

public double getI_m(){ 
    return this.i_m; 
} 

public String getIdSentence(){ 
    return this.idSentence; 
} 

public String toString(){ 
    return this.supporto+" - "+this.i_m+" - "+this.idSentence; 
} 
}

，並添加一個ArrayList文本這些值：

ArrayList<Media> m=new ArrayList<Media>(); 
m.add(new Media(0.2545,0.2365,"id002")); 
m.add(new Media(0.8745,0.4658,"id005")); 
m.add(new Media(0.1599,0.6580,"id0010"));

我怎麼排序此數組中值的降序排列一流的媒體？我想這個命令：

0.1599,0.6580,"id0010" 
0.2545,0.2365,"id002" 
0.8745,0.4658,"id005"

編輯

我解決了這個辦法：

public class Media implements Comparable<Object>{ 
double supporto; 
double i_m; 
String idSentence; 

public Media(double supporto,double i_m,String idSent){ 
this.supporto=supporto; 
this.i_m=i_m; 
this.idSentence=idSent; 
} 
public double getSupporto(){ 
return this.supporto; 
} 
public double getI_m(){ 
return this.i_m; 
} 
public String getIdSentence(){ 
return this.idSentence; 
} 
public String toString(){ 
return this.supporto+" - "+this.i_m+" - "+this.idSentence; 
} 
@Override 
public int compareTo(Object arg0) { 
    if(this.supporto==((Media) arg0).getSupporto()) return 0; 
    else if((this.supporto)>((Media)arg0).getSupporto()) return 1; 
    else return -1; 
} 
}

在main方法我下令將M的ArrayList：

Collections.sort(m);

來源

2014-10-09 Enzo

向我們展示您嘗試實施分類的代碼。 – 2014-10-09 10:08:57

使用Comparable或Comparator對對象進行排序 – 2014-10-09 10:08:59

實現Comparable或Comparator並使用Collections.sort（）方法 – DeiAndrei 2014-10-09 10:09:34

你需要做水果比較

public class Media implements Comparable<Fruit> { 
    public int compareTo(Fruit compareFruit) { 

     int compareQuantity = ((Media) compareFruit).getSupporto(); 

     //ascending order 
     return this.supporto - compareQuantity; 

     //descending order 
     //return compareQuantity - this.supporto; 
    } 
... 
}

Arrays.sort（m）; 一些更多的信息： http://www.mkyong.com/java/java-object-sorting-example-comparable-and-comparator/

來源

2014-10-09 10:11:37 rjdkolb

你可以用自己的比較排序呢

m.sort(new Comparator<Media>() { 

     @Override 
     public int compare(Media o1, Media o2) { 
      return Double.compare(o1.getSupporto(), o2.getSupporto()); 
     } 
    });

這將你喜歡的方式排序。如果您需要這在許多pleaces，我會但是建議創建靜態比較，如：

private static Comparator<Media> supportoComparator = new Comparator<Media>() { 

    @Override 
    public int compare(Media o1, Media o2) { 
     if (o1 != null && o2 != null) { 
      return Double.compare(o1.getSupporto(), o2.getSupporto()); 
     } else { 
      throw new IllegalArgumentException(); 
     } 
    } 
};

上面的代碼是在類媒體，然後你使用它像：

m.sort(Media.GET_SUPPORTO_COMPARATOR());

，並對其做

來源

2014-10-09 10:13:00

的Java：ArrayList中我如何才能

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