oiu1010110 于 2016.04.23 13:22 提问

java 集合排序问题，谢谢指导。

ListrationalList = new ArrayList<>();
Collections.sort(rationalList,new InverseComparator());
public class InverseComparator implements Comparator {
// 比较两个分数倒数的大小
@Override
public int compare(Rational obj1, Rational obj2) {
Rational ra1 = obj1;
Rational ra2 = obj2;
int nm1 = obj1.getNumerator();
int dm1 = obj1.getDenominator();
ra1.setDenominator(nm1);
ra1.setNumerator(dm1);

``````    int nm2 = obj2.getNumerator();
int dm2 = obj2.getDenominator();
ra2.setDenominator(nm2);
ra2.setNumerator(dm2);  这里这样的话就改变了原来的分数，后面输出来的都是倒数，而不是原来的分数，怎么写呢要？
//……
}
}
``````

3个回答

oiu1010110   2016.04.23 19:58

public int compare(Rational obj1, Rational obj2) {

``````    int nm1 = obj1.getNumerator();
int dm1 = obj1.getDenominator();
Rational ra1 = null;
try {
ra1 = new Rational(dm1,nm1);
} catch (IllegalRationalException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

int nm2 = obj2.getNumerator();
int dm2 = obj2.getDenominator();
Rational ra2 = null;
try {
ra2 = new Rational(dm2,nm2);
} catch (IllegalRationalException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//……这里用前面本身排序的compareTo();只是参数换成了两个比较
}

//已解决
``````
CSDNXIAOD   2016.04.23 13:32

java集合排序问题
Java集合中的排序问题
Java集合中的排序问题
----------------------biu~biu~biu~~~在下问答机器人小D，这是我依靠自己的聪明才智给出的答案，如果不正确，你来咬我啊！

molashaonian   2016.04.23 15:15

class Name implements Comparable{

public String firstName,lastName;

public Name(String firstName,String lastName){

this.firstName=firstName;

this.lastName=lastName;

}

public int compareTo(Name o) { //实现接口

int lastCmp=lastName.compareTo(o.lastName);

return (lastCmp!=0?lastCmp:firstName.compareTo(o.firstName));

}

public String toString(){ //便于输出测试

return firstName+" "+lastName;

}

}