关系操作符 == != equals()

2018-11-13 07:34:27来源：博客园阅读 ()

== 和!=

//: object/test.java

package object;
import java.util.*;

public class Test{
    public static void main(String[] args)
    {
        Integer n1 = new Integer(47);
        Integer n2 = new Integer(47);
        System.out.println(n1 == n2);//output false
        System.out.println(n1 != n2);//output true
    }
}
//比较的是对象的引用

equals:equals 不适用于基本类型,基本类型用== !=

//: object/test.java

package object;
import java.util.*;

public class Test{
    public static void main(String[] args)
    {
        int n1 = 100;
        int n2 = 100;
        System.out.println(n1==n2);//output false
    }
}

equals

//: object/test.java

package object;
import java.util.*;

public class Test{
    public static void main(String[] args)
    {
        Integer n1 = new Integer(47);
        Integer n2 = new Integer(47);
        System.out.println(n1.equals(n2));//output true
    }
}

equals:假如自己创建自己的类情况又不一样

//: object/test.java

package object;
import java.util.*;

class Value{
    int i;
}

public class Test{
    public static void main(String[] args)
    {
        Value n1 = new Value();
        Value n2 = new Value();
        n1.i = n2.i = 100;
        System.out.println(n1.equals(n2));//output false
    }
}