java – 在if-else子句之外无法识别的对象

发布时间：2020-12-15 04:08:39 所属栏目：Java 来源：网络整理

导读：在if-else分支中,我声明了两个具有相同名称的不同PrintStream对象.但是,当我稍后使用PrintStream对象时,编译器会说它“找不到符号”.为什么不看到我创建的对象？该对象使用它声明的if-else分支.这是代码： System.out.println("Welcome. Would you like to c

在if-else分支中,我声明了两个具有相同名称的不同PrintStream对象.但是,当我稍后使用PrintStream对象时,编译器会说它“找不到符号”.为什么不看到我创建的对象？该对象使用它声明的if-else分支.这是代码：

System.out.println("Welcome. Would you like to continue a previous adventure,or begin anew?n(type: new or old)");
status = scan.nextLine();

if(status.equals("new")) {
    System.out.println("What do you call yourself?");
    name = scan.nextLine();

    System.out.println("And what shall be the title of your saga,after you are gone?");
    game = scan.nextLine();

    System.out.println("Very well. Prepare yourself,for this is the beginning of your end...n...n...nAre you ready?");
    status = scan.nextLine();

    System.out.println("Not that it matters. Let us begin.");
    status = scan.nextLine();

    File file = new File(game + ".txt");
    PrintStream print = new PrintStream(file);
    print.println(name);
    old = false;
} else {
    System.out.println("So you're still alive? What was the title of your tale?");
    game = scan.nextLine();

    File file = new File(game + ".txt");
    Scanner gscan = new Scanner(file);
    String save = "";

    while (gscan.hasNextLine()) {
        save += gscan.nextLine();
        save += "n";
    }

    System.out.println(save);
    PrintStream print = new PrintStream(file);
    print.println(save);

    old = true;
    name = scan.nextLine();
}

if(old) {

}

print.println("beans");

解决方法

您需要在if语句之外声明变量,然后在两个分支中分配它,如下所示：

PrintStream print;
if (status.equals("new")) {
    ...
    print = new PrintStream(file);
} else {
    ...
    print = new PrintStream(file);
}

更好的是,您可以在if中设置文件,然后在条件之后创建PrintStream：

if (status.equals("new")) {
    ...
} else {
    ...
}
File file = new File(game + ".txt");
PrintStream print = new PrintStream(file);

（编辑：李大同）

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