在Java中,for循环和if语句内部的布尔返回语句始终返回false。

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英文:

The boolean return statement inside a for loop and if statement is always returning false in java

问题

尝试从函数 "checkUser" 返回一个布尔输出,然后打印相应的输出。但是每次运行时,即使条件正确,它总是返回 'false'。我使用了一个对象来保存布尔结果,因为在 'if' 内部返回语句不起作用。

此外,在 'getCheck()' 函数中出现了提示 "method breakpoint"。我是否有什么错误?

import java.util.Scanner;

class myclass {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Bank[] bk = new Bank[4];
        System.out.println("Enter the Name, Age and the Acc No. of 3 users: ");
        for (int i = 0; i < 3; i++) {
            String name = sc.next();
            int age = sc.nextInt();
            int acc_no = sc.nextInt();
            bk[i] = new Bank(name, age, acc_no);
        }
        System.out.println("Enter the Account no to validate a user: ");
        int acc_chk = sc.nextInt();

        // 调用方法
        boolean c = checkUser(bk, acc_chk);

        // 输出
        if (c)
            System.out.println("The user account exists!");
        else
            System.out.println("The user account does not exist!");
    }

    // 检查用户的真实性方法
    public static boolean checkUser(Bank[] obj, int ac_no) {
        int j = 0;
        for (int i = 0; i < 3; i++) {
            if (ac_no == obj[i].getAcc()) {
                obj[i].setCheck(true);
                j = i;
            }
        }
        return obj[j].getCheck();
    }
}

class Bank {
    String name;
    int age;
    int acc;
    String type;
    boolean check;

    public Bank(String s, int a, int b) {
        name = s;
        age = a;
        acc = b;
    }

    public void setName(String s) { this.name = s; }
    public void setAge(int a) { this.age = a; }
    public void setAcc(int b) { this.acc = b; }
    public void setType(String t) { this.type = t; }
    public void setCheck(boolean ch) { this.check = ch; }

    public String getName() { return name; }
    public int getAge() { return age; }
    public int getAcc() { return acc; }
    public String getType() { return type; }
    public boolean getCheck() { return check; }
}
英文:

I am trying to return a boolean output from the function "checkUser" and then to print an output for that. But for every run, it is always returning 'false' even though the conditions are correct. I have used an object to save the boolean result because the return statement is not working inside the 'if'.
Also, I am getting the prompt- 'method breakpoint' in 'getCheck()' function. Is there any thing wrong I am doing?

import java.util.Scanner;
class myclass {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
Bank[] bk=new Bank[4];
System.out.println(&quot;Enter the Name, Age and the Acc No. of 3 users : &quot;);
for(int i=0; i&lt;3; i++) {
//System.out.print(&quot;Enter the Name : &quot;);
String name=sc.next();
//System.out.print(&quot;Enter the age : &quot;);
int age=sc.nextInt();
//System.out.print(&quot;Enter the Account Number : &quot;);
int acc_no=sc.nextInt();
bk[i]=new Bank(name, age, acc_no);
}
System.out.println(&quot;Enter the Account no to validate a user : &quot;);
int acc_chk=sc.nextInt();
// method calling
boolean c=checkUser(bk, acc_chk);
// Outputs
if(c)
System.out.println(&quot;The user account exits!&quot;);
else
System.out.println(&quot;The user account does not exit!&quot;);
}
// method to check the authenticity of the user
public static boolean checkUser(Bank[] obj, int ac_no) {
//boolean ch;
int j=0;
for(int i=0; i&lt;3; i++) {
if(ac_no==obj[i].getAcc()) {
obj[i].setCheck(true);
j=i;
}
}
return obj[j].getCheck();
}
}
class Bank{
String name;
int age;
int acc;
String type;
boolean check;
public Bank(String s, int a, int b) {
}
public void setName(String s) {this.name=s;}
public void setAge(int a){this.age=a;}
public void setAcc(int b){this.acc=b;}
public void setType(String t) {this.type=t;}
public void setCheck(boolean ch){this.check=ch;}
public String getName() {return name;}
public int getAge() {return age;}
public int getAcc() {return acc;}
public String getType() {return type;}
public boolean getCheck() {return check;}
}

答案1

得分: 0

谢谢你的帮助,除了构造函数 Bank 外,一切都是正确的,而且一切都运行得很好。构造函数没有调用设置器,所以值没有存储在任何变量中,这就是为什么布尔变量的默认值是 false,这个值被 checkUser 函数返回。谢谢 @FedericoklezCulloca,我尝试打印中间值,但什么都没有打印出来,所以当我去检查构造函数时,我找到了错误。

public Bank(String s, int a, int b) {
    this.setName(s);
    this.setAge(a);
    this.setAcc(b);
}
英文:

Thanks for helping me, everything was right and was working perfectly fine except the constructor Bank. It was not calling the setters so values were not stored in any variable and that's why boolean variable had the default value false which was returned by the function checkUser. Thanks @FedericoklezCulloca, I tried to print the intermediate values but nothing was printing so when I went to check the constructor I found the fault.

public Bank(String s, int a, int b) {
this.setName(s);
this.setAge(a);
this.setAcc(b);
}

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  • 本文由 发表于 2020年7月24日 21:32:33
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