將數組傳遞給不同的類...閱讀NetBeans Java

Question

A.java

public Class A 
{ 

     String a,b; 
     public static void setArray(String[] array)//This is where i want the array to come 
     { 
       array[0]=a; 
       array[1]=b 
     } 
} 

B.java

public class B 
{ 

     String[] arr1 = new String[2]; 
     arr1[0]="hello"; 
     arr1[2]="world"; 
     public static void main(String[] args) 
       { 
       A a = new A(); 
       a.setArray(arr1);//This is from where i send the array 
       } 
} 

我試圖從一個類發送一個陣列到另一個類

Answer 1

我已經編輯了一下你的代碼。你的主要問題是在A類中，你正在向後分配值。查看更新的類A.我還爲您的類添加了構造函數，但這不是必需的。

public Class A { 

    String a,b; 

    // A public method with no return value 
    // and the same name as the class is a "class constructor" 
    // This is called when creating new A() 
    public A(String[] array) 
    { 
    setArray(array) // We will simply call setArray from here. 
    } 

    private void setArray(String[] array) 
    { 
    // Make sure you assign a to array[0], 
    // and not assign array[0] to a (which will clear this array) 
    a = array[0]; 
    b = array[1]; 
    } 
} 

public class B { 
    String[] arr1 = new String[2]; 
    arr1[0]="hello"; 
    arr1[2]="world"; 
    // A a; // You can even store your A here for later use. 
    public static void main(String[] args) 
    { 
    A a = new A(arr1); // Pass arr1 to constructor when creating new A() 
    } 
} 

Answer 2

由於您的類A中的字符串變量未初始化，您正在獲取NULL值。

在A類，你需要從方法消除靜電，並與一些初始化字符串a和b，像這樣：

public class A { 
    String a = "bye"; 
    String b = "bye"; 

    public void setArray(String[] array) { 
     array[0] = a; 
     array[1] = b; 
    } 
} 

在B類，你應該添加靜態到您的陣列（也可以不在靜態方法中引用一個非靜態變量）。

public class B { 
    static String[] arr1 = {"hello", "world"}; 
    public static void main(String[] args) { 
     A a = new A(); 
     a.setArray(arr1);//This is from where i send the array 
     System.out.println(arr1[0] + " " + arr1[1]); 
    } 
} 

另外，如果你要初始化的東西，你做的方式（方法外）：

String[] arr1 = new String[2]; 
arr1[0]="hello"; 
arr1[2]="world"; 

你必須把塊內的初始化，像這樣：

String[] arr1 = new String[2]; 
{ 
    arr1[0] = "hello"; 
    arr1[2] = "world"; 
} 

希望這可以幫助你