Question

我想比较来自Scanner的三对输入（只是快速测试）使用Compare方法。

当我运行此程序时，它会为所有三个输入返回false，即使它们之间应该有true。当我删除Scanner并自己输入String时，我会得到正确的结果

首先我认为它是由额外的＆＃34; Enter＆＃34;引起的。保留在缓冲区中的按钮，但是当我调试它时，缓冲区中没有任何不需要的东西并且额外的输入要求不会得到任何帮助。

import java.util.Scanner; 

 public class MainSector {
    String Primary, Secondary;

    MainSector(String Primary, String Secondary){
        this.Primary = Primary;
        this.Secondary = Secondary;
    }

MainSector(int Primary, int Secondary) {
    this.Primary = String.valueOf(Primary);
    this.Secondary = String.valueOf(Secondary);
    }

boolean Compare(MainSector x){
    return (x.Primary == Primary && x.Secondary == Secondary );

    }

}


public class Test {
    public static void main(String[] args) {
        Scanner u = new Scanner(System.in);
        Scanner y = new Scanner(System.in);

        System.out.println("Enter String:");
        MainSector Sector1 = new MainSector(u.nextLine(),y.nextLine());

        System.out.println("Enter String:");
        MainSector Sector2 = new MainSector(u.nextLine(),y.nextLine());

        System.out.println("Enter Integer:");
        MainSector Sector3 = new MainSector(u.nextInt(),y.nextInt());


        System.out.println(Sector1.Compare(Sector2));
        System.out.println(Sector1.Compare(Sector3));
        System.out.println(Sector2.Compare(Sector3));


    }
}

即使前两个输入完全相同，它也会在此返回false三次。例如，我得到了正确的结果：

System.out.println("Enter String:");
MainSector Sector1 = new MainSector("aa","bb");

System.out.println("Enter String:");
MainSector Sector2 = new MainSector("aa","bb");

System.out.println("Enter Integer:");
MainSector Sector3 = new MainSector(45,65);

它返回：

true

false

Answer 1

你的问题在于你的比较方法;使用==比较参考值。由于您在比较中使用了不同的对象，因此在这种情况下它们永远不会具有相同的参考值。您需要使用.equals(Object)来比较确切的值。我编辑了下面的代码来反映这一点并进行了测试。
此外，你真的不需要2个扫描仪来做这个，你可以使用一个！一如既往，请记得关闭扫描仪;这是一种很好的做法。

import java.util.Scanner; 



 class MainSector {
    String Primary, Secondary;

    MainSector(String Primary, String Secondary){
        this.Primary = Primary;
        this.Secondary = Secondary;
    }

MainSector(int Primary, int Secondary) {
    this.Primary = Integer.toString(Primary);
    this.Secondary = Integer.toString(Secondary);
    }

//Note the changes made to this method!
    boolean Compare(MainSector x){
        return ((x.Primary.equals(Primary)) && (x.Secondary.equals(Secondary)));

        }
} //End MainSector


public class Test {
    public static void main(String[] args) {
        Scanner u = new Scanner(System.in);

        System.out.println("Enter String:");
        MainSector Sector1 = new MainSector(u.nextLine(),u.nextLine());

        System.out.println("Enter String:");
        MainSector Sector2 = new MainSector(u.nextLine(),u.nextLine());

        System.out.println("Enter Integer:");
        MainSector Sector3 = new MainSector(u.nextInt(),u.nextInt());


        System.out.println(Sector1.Compare(Sector2));
        System.out.println(Sector1.Compare(Sector3));
        System.out.println(Sector2.Compare(Sector3));

        u.close();
    } //End main
} //End Test

我找到了一篇很棒的文章，如果你想了解更多，我会在这里详细解释答案：How do I compare Strings in Java?

java scanner＆same-exact-inputs不相等（对我来说？）

1 个答案: