java - 在带有字符串长度方法的 "or"语句中使用 "if"语句

Question

所以在我的第五行代码 [if(length == 2 || 1)] 我的 or 语句出现错误，说运算符 ||对于参数类型 boolean、int 未定义。关于我的语法有什么问题以及如何解决它的任何想法？谢谢!

//Write a program that translates a letter grade into a number grade. Letter grades are
//A B C D F, possibly followed by + or -. Their numeric values are 4, 3, 2, 1, and 0.
//There is no F+ or F-. A + increases the numeric value by 0.3, a - decreases it by     0.3.
//However, an A+ has the value 4.0. All other inputs have value –1.
//Enter a letter grade:

//使用带有方法 getNumericGrade 的类 Grade。

public class Grade {
private double grade = 0.0;
public double getNumericGrade(String letterGrade){
    int length = letterGrade.length();
    if(length == 2 || 1){
        char startChar = letterGrade.charAt(0);
        char endChar = letterGrade.charAt(1);
        switch(startChar){
        case 'A':
            this.grade = 4.0;
            break;
        case 'B':
            this.grade = 3.0;
            break;
        case 'C':
            this.grade = 2.0;
            break;
        case 'D':
            this.grade = 1.0;
            break;
        case 'F':
            this.grade = 0.0;
            break;
        default:
            this.grade = -1;
        }
    if(length == 2){
        switch(endChar){
        case '-':
            this.grade = this.grade - .3;
            break;
        case '+':
            if(startChar != 'A'){
            this.grade = this.grade + .3;
            }
            break;
        default:
            this.grade = -1;
        }
    }
    if(startChar == 'F' && length != 1){
        this.grade = -1;
    }
    }else{
        this.grade = -1;
    }
    return this.grade;
}

Answer 1

这意味着 || 运算符不接受 boolean 值和整数，您必须给它两个 boolean 表达式。

if(length == 2 || length ==  1)