java - sb 无法解析为变量

Question

我尝试了这段代码，它适用于其他人，但不适合我:

//import java.lang.*;


public class Main {

    public static void main(String[] args) {
        String[][] states = new String[3][2];   
        states[0][0]="california";
        states[0][1]="scremanto";
        states[1][0]="oregan";
        states[1][1]="salem";
        states[2][0]="newyork";
        states[2][1]="chicago";

        for (int i = 0; i < states.length; i++) {
            StringBuilder sb = new StringBuilder();
            for (int j = 0; j < states[i].length; j++) {
                sb.append(states[i][j]);
            }
        }
        System.out.println(sb);
    }
}

我得到的错误是:

Exception in thread "main" java.lang.Error: Unresolved compilation problem: sb cannot be resolved to a variable

at Main.main(Main.java:23)

注意:我使用 Eclipse，也许这很有意义。

Answer 1

您在 i for 内部定义 sb 并尝试在其外部引用它，如您所见，这是行不通的。看来您打算在循环之外定义它:

StringBuilder sb = new StringBuilder();
for (int i = 0; i < states.length; i++) {
    for (int j = 0; j < states[i].length; j++) {
        sb.append(states[i][j]);
    }
}

System.out.println(sb);