实施例

Question

我是第二年的CS学生，并尝试修复一个简单的方法。逻辑相当容易，但不知怎的，我仍然得到一个错误，虽然我不知道这里有什么问题。

问题：

班级的开头：

private Integer dt[];
private int size;
IntManager(int k){
    dt = new Integer[k]; 
    size = 0;
}

班级内的方法：

public Integer max(){
  //return largest value in dt; null if size == 0
    if (size == 0) return null;
    else{
        Integer biggest = dt[0];//trouble here; changing to int won't help & var name also  
        for (int j = 0; j < size ; j++) {
            if (dt[j] < biggest) biggest = dt[j];
        }
    }
    return biggest;
}

主要课程：

IntManager num = new IntManager(100);
    for (int j = 0; j < 20 ; j++) {
        int x = (int)(Math.random()*10);
        num.add(x);
    }
    num.add(57);
    System.out.println(num);

    System.out.println(num.found(5));//Ignore this


    System.out.println(num.max());

Answer 1

您的最大变量是在ifelse范围内定义的，因此在该细分受众群之外是不可见的将Integer声明为一个孔方法变量......

实施例

public Integer max(){
      Integer biggest=null;
        if (size != 0) {
            Integer biggest = dt[0]; 

            for (int j = 0; j < size ; j++) {
                if (dt[j] < biggest) biggest = dt[j];
            }
        }
        return biggest;
    }

Answer 2

问题在于你的块

public Integer max(){
 //return largest value in dt; null if size == 0
    if (size == 0) return null;
    else{
        Integer biggest = dt[0];//trouble here; changing to int won't help     & var name also  
        for (int j = 0; j < size ; j++) {
            if (dt[j] < biggest) biggest = dt[j];
        }
    }
    return biggest;
}

您在该else块的范围内声明最大值，因此当您到达return语句时它不可见。要纠正它，你应该有类似的东西：

public Integer max(){
 //return largest value in dt; null if size == 0
    Integer biggest = dt[0]
    if (size == 0) return null;
    else{
        ;//trouble here; changing to int won't help     & var name also  
        for (int j = 0; j < size ; j++) {
            if (dt[j] < biggest) biggest = dt[j];
        }
    }
    return biggest;
}

return语句找不到方法内的局部变量

2 个答案:

实施例