Question

import java.util.Scanner;


public class Main {


public static void main(String[] args) {
    boolean x;


    Scanner sc = new Scanner(System.in);

    String igual = sc.next().toString();        

    String[] yes = new String[15];
    yes[0]="When I find myself in times of trouble";
    yes[1]="Mother Mary comes to me";
    yes[2]="Speaking words of wisdom";
    yes[3]="Let it be ";
    yes[4]="And in my hour of darkness ";
    yes[5]="She is standing right it front of me ";
    yes[6]="mama just killed a man";
    yes[7]="And when the broken hearted people ";
    yes[8]="Living in the world agree ";
    yes[9]="There will be an answer ";
    yes[10]="For though they may be parted";
    yes[11]="there is still a chance that they will see";
    yes[12]="And when the night is cloudy";
    yes[13]="There is still a light that shines on me";
    yes[14]="Shine until tomorrow";

    String[] no = new String[5];
    no[0]="I wake up to the sound of music";
    no[1]="Mother Mary comes to me";
    no[2]="put a gun against his head";
    no[3]="pulled my trigger now his dead";
    no[4]="mama life had just began";

    // searches in the yes array
    for (int i=0 ; i<yes.length ; i++){
    x=igual.trim().equalsIgnoreCase(yes[i].trim());

    if (x=true){
        System.out.println("true");
    }
    }

            //searches in the no array
    for (int j=0 ; j<no.length ; j++){
    x = igual.trim().equalsIgnoreCase(no[j].trim());
    if (x=true){
        System.out.println("false");
    }
    }

}

}

打印15次真实 5次假即使您输入的字符串只等于数组中的一个字符串。我对代码进行了验证，结果就是这些看起来它在'if'条件中设置'x'变量先感谢您。

Answer 1

作业将返回右侧。因此（来自您的if - 声明条件）：

x=true

始终返回true。您可能正在寻找x == true或更常规的x（如if (x) {...}所示）。通常应该更倾向于更简单的第二种变体。

Answer 2

使用x == true，一个等式表达式，而不是x = true，这是一个赋值表达式。

JLS chapter 15.26说这个

在运行时，赋值表达式的结果是值分配发生后的变量。

所以，在代码中

if (x = true)

x被分配true，然后if评估true。因此，无论您从equalsIgnoreCase获得什么值，语句都将始终进入if块，因为赋值表达式将返回true。

此外，您不需要对布尔值进行条件检查。你可以简单地使用

if (x) { // read as if x is true
    ...
}

为什么即使对于非相等的字符串，equalsignorecase也会返回true

2 个答案: