Java Tester文件返回null

Question

我想使用一个测试文件读取几个对象，但是我从步骤2到步骤4的空。

为姓名，如果我输入史蒂文，我想退回ste123（123应该是一个随机号码）

这是代码：

public class Lab14Tester
{
    public static void main(String[] args)
    {
        Introduction step1 = new Introduction();
        System.out.println(step1.giveline1());
        System.out.println(step1.giveline2());
        System.out.println(step1.giveline3());
        System.out.println(step1.giveline2());
        System.out.println(step1.giveline1());
        Scanner in= new Scanner(System.in);
        System.out.print("nName: "); 
        String inputname = in.nextLine();
        Username step2 = new Username();
        String givename = step2.givename();
        System.out.println("Your username is " + givename);
        System.out.print("nGive me a number: ");
        int inputnumber =in.nextInt();
        OddEven step3 = new OddEven();
        System.out.println(step3.givenumbertype());
        System.out.print("nGive me a number grade: ");
        double grade = in.nextDouble();
        NumberToLetter step4 = new NumberToLetter();
        System.out.printf("n%.1f", grade);
        System.out.print(" is equal to a " + step4.giveletter());
    }
}

public class Username
{
    private String subname;
    private int randomnumber;
    private String outputname;
    public void getname(String inputname)
    {
        subname = inputname.substring(0,3);
        randomnumber = (int)(Math.random()*1000);
        outputname = subname + randomnumber;
    }
    public String givename()
    {
        return outputname;
    }
}

Answer 1

您可能会遇到麻烦，因为您将字符串与整数串联。

尝试以下操作：

public void getname(String inputname)
{
    subname = inputname.substring(0,3);
    randomnumber = (int)(Math.random()*1000);
    String randomnumberAsString = String.valueOf(randomnumber);
    outputname = subname + randomnumberAsString;
}