Java 变量的可见性控制

您已经在ArrayLesson1类中声明了数组，该数组对您的子类不可见，因此您得到了编译错误

你有两个选择

1在子类中创建构造函数以接受数组作为参数，并在子类中创建局部变量，然后将数组从ArrayLesson1传递给子类，如下所示：

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

at Array.subclass.loopj(ArrayLesson1.java:40)   
at Array.ArrayLesson1.main(ArrayLesson1.java:25)

//in subclass
private int [] array;
public subclass(int [] array) {
   this.array = array;
}

public static void loopj(int [] array) {
   //Codes here
//

obj.loopj(array);

在ArrayLesson1类中这样调用：

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

at Array.subclass.loopj(ArrayLesson1.java:40)   
at Array.ArrayLesson1.main(ArrayLesson1.java:25)

//in subclass
private int [] array;
public subclass(int [] array) {
   this.array = array;
}

public static void loopj(int [] array) {
   //Codes here
//

obj.loopj(array);

2修改loopj和loopk方法，以接受数组作为参数，如下所示：

subclass obj=new subclass(array); // Pass array like this

在你的数组中调用它，如下所示：

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

at Array.subclass.loopj(ArrayLesson1.java:40)   
at Array.ArrayLesson1.main(ArrayLesson1.java:25)

//in subclass
private int [] array;
public subclass(int [] array) {
   this.array = array;
}

public static void loopj(int [] array) {
   //Codes here
//

obj.loopj(array);

3或者，如果要使用静态引用，则需要在使用它之前与classname.variablename一起使用，如下所示：

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

at Array.subclass.loopj(ArrayLesson1.java:40)   
at Array.ArrayLesson1.main(ArrayLesson1.java:25)

//in subclass
private int [] array;
public subclass(int [] array) {
   this.array = array;
}

public static void loopj(int [] array) {
   //Codes here
//

obj.loopj(array);

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