在java打印和返回數組

Question

我是新來的java，我正在做一些練習來學習。我一直在處理數組，並且已經能夠打印出我的第一個數組。但第二個不打印任何東西，只是想知道我出錯的地方，非常感謝。

package Justice; 

import java.util.Arrays; 

class ArrayDemo { 
    public static void main(String[] args) { 
    int[] anArray; 

    anArray = new int[10]; 

    anArray[0] = 100; 
    anArray[1] = 200; 
    anArray[2] = 300; 
    anArray[3] = 400; 
    anArray[4] = 500; 
    anArray[5] = 600; 
    anArray[6] = 700; 
    anArray[7] = 800; 
    anArray[8] = 900; 
    anArray[9] = 1000; 
    System.out.println (Arrays.toString(anArray)); 

} 


public static String[] hello(String[] args) { 
    String[] myArray; 


    myArray = new String[5]; 
    myArray[0] = "hello"; 
    myArray[2] = "world"; 

    System.out.println(Arrays.toString(myArray)); 
    return (myArray); 

} 

Answer 1

只有當你從shell中運行Java類

被調用。

如果你想打電話

hello(String[] args) 

您必須在主法明確地調用它。您可以添加您的第一個print語句下面的行：

hello(null); 

Answer 2

請嘗試deepToString(Object[])方法，而不是toString(args)。

您可以嘗試使用方法deepToString(Object[])來顯示該數組的所有內容。

String [] arr = new String[3]; 
arr[0]="asdf"; 
arr[1]="asdf"; 
System.out.println(Arrays.deepToString(arr)); 

將打印輸出等爲

[asdf, asdf, null] 

另一種方式做，這是... 你也可以遍歷數組在服用長度在for循環一個標準。

for(int i=0 i<anArray.length;i++) 
System.out.println(anArray[i]); 

感謝您

Answer 3

粘貼此System.out.println(hello(args));後的System.out.println（Arrays.toString（anArray））;

會給你輸出：[hello, null, world, null, null]

Answer 4

只需添加到您的代碼

package Justice; 

import java.util.Arrays; 

class ArrayDemo { 
    public static void main(String[] args) { 
    int[] anArray; 

    anArray = new int[10]; 

    anArray[0] = 100; 
    anArray[1] = 200; 
    anArray[2] = 300; 
    anArray[3] = 400; 
    anArray[4] = 500; 
    anArray[5] = 600; 
    anArray[6] = 700; 
    anArray[7] = 800; 
    anArray[8] = 900; 
    anArray[9] = 1000; 
    System.out.println (Arrays.toString(anArray)); 

    // This is the method call 
    hello(null);    // You don't need the 'String[] args' in your method because you've not used the arguments 


} 


public static String[] hello(String[] args) { 
    String[] myArray; 


    myArray = new String[5]; 
    myArray[0] = "hello"; 
    myArray[2] = "world"; 

    System.out.println(Arrays.toString(myArray)); 
    return (myArray); 

} 

Answer 5

只要改變你的main()這樣：

class ArrayDemo { 
public static void main(String[] args) { 

int[] anArray; 

anArray = new int[10]; 

anArray[0] = 100; 
anArray[1] = 200; 
anArray[2] = 300; 
anArray[3] = 400; 
anArray[4] = 500; 
anArray[5] = 600; 
anArray[6] = 700; 
anArray[7] = 800; 
anArray[8] = 900; 
anArray[9] = 1000; 
System.out.println (Arrays.toString(anArray)); 

ArrayDemo obj = new ArrayDemo(); 
obj.hello(); 
} 

，使hello()方法是這樣的：

public void hello() { 
String[] myArray; 


myArray = new String[5]; 
myArray[0] = "hello"; 
myArray[2] = "world"; 

System.out.println(Arrays.toString(myArray)); 
} 

Answer 6

public static String [] hello（String [] args）不被調用。它應該從public static void main（）中調用。