java - 类型不匹配：无法从 int 转换为 String

Question

public String getMessage (int numEggs) {

    int a = numEggs/12;
    int b = numEggs%12;

    if ( numEggs < 0) {
        System.out.println("Invalid number");
    } else {
        System.out.println("Your number of eggs is "+ a +" dozen(s) and "+ b+".");
        return;
    }
}

因此，Type mismatch: cannot convert from int to String当我尝试在回报中放入一些东西时，我会不断得到；代码有什么问题？我必须使用getMessage (int numEggs)它，因为它是我提出的问题的一部分。

Answer 1

当我尝试将某些内容放入返回时，无法从 int 转换为 String，

该方法期望您返回一个字符串。所以你不能这样做：

return 1; //ie 1, does not get automatically converted to "1"

但你可以这样做：

return "I'm a String";

Answer 2

我不明白Type mismatch: cannot convert from int to String，但错误是：This method must return a result of type String

您的方法中缺少 return 语句：

public String getMessage(int numEggs) {

    int a = numEggs / 12;
    int b = numEggs % 12;

    if (numEggs < 0) {
        return "Invalid number";
    } else {
        return "Your number of eggs is " + a + " dozen(s) and "
                + b + ".";          
    }
}

即使我将getMessage返回类型更改为void它也不会给我Type mismatch: cannot convert from int to String

public void getMessage(int numEggs) {

    int a = numEggs / 12;
    int b = numEggs % 12;

    if (numEggs < 0) {
        System.out.println("Invalid number");
    } else {
        System.out.println("Your number of eggs is " + a + " dozen(s) and "
                + b + ".");
        return;
    }
}

Answer 3

你需要返回一个字符串吗？如果您只想打印，只需将返回类型设为 void 并删除底部的“返回”即可。

Answer 4

如果你想返回一个字符串：

公共字符串 getMessage (int numEggs) {

int a = numEggs/12;
int b = numEggs%12;
String strReturn = "";

if ( numEggs < 0) {
    strReturn = "Invalid number";
} else {
    strReturn = "Your number of eggs is "+ a +" dozen(s) and "+ b+".";

}
return strReturn;

}

如果您想在控制台中打印它，那么

公共无效getMessage（int numEggs）{

int a = numEggs/12;
int b = numEggs%12;

if ( numEggs < 0) {
    System.out.println("Invalid number");
} else {
    System.out.println("Your number of eggs is "+ a +" dozen(s) and "+ b+".");
}

}