Java比較器-比較列表中的2個不同的對象

Question

我在Java中有以下課程，我想將list中的tocompare對象與之前的tocompare對象進行比較， tocompare t2與t1比較。

我是Java的新手，所以我對如何做到這一點並不了解。

public class ToCompare {
    private String property1;
    private String property2;

    public void getProperty1(){
        return property1;
    }
    public void setProperty1(String property1){
        this.property1 = property1;
    }

    public void getProperty2(){
        return property2;
    }
    public void setProperty1(String property2){
        this.property2 = property2;
    }
}

List<ToCompare> tocompare = new ArrayList();
ToCompare t1 = new ToCompare();
ToCompare t2 = new ToCompare();
ToCompare t3 = new ToCompare();
ToCompare t4 = new ToCompare();

tocompare.add(t1); //obj1
tocompare.add(t2); //obj2
tocompare.add(t3); //obj3
tocompare.add(t4); //obj4

for (String comp : tocompare) {
    // compare properties of 2nd ToCompare object with 1st ToCompare object
}

Answer 1

使用Comparable接口並實現compareTo方法，該方法定義比較策略-https: //docs.oracle.com/javase/7/docs/api/java/lang/Comparable.html

例如，如果您要根據property1比較它們-

public class ToCompare implements Comparable<ToCompare> {
    private String property1;
    private String property2;

    public void getProperty1(){
        return property1;
    }

    public void setProperty1(String property1){
        this.property1 = property1;
    }

    public void getProperty2(){
        return property2;
    }

    public void setProperty1(String property2){
        this.property2 = property2;
    }

    @Override
    public int compareTo(ToCompare toCompare){  
        return this.getProperty1().compareTo(i.getProperty1()); 
   }  
}