Question

Java表示存在预期的“]”错误。我找不到我的代码有什么问题？ Song类是另一个类组合类，没有问题。提前感谢您的帮助

public class Jukebox
{
    Song[][] songList;

    songList[0][0] = new Song("Jet Airliner", 5 );

    songList[0][1] = new Song( "Slide", 4 );

    songList[0][2] = new Song( "Tom Sawyer", 3 );
    songList[0][3] = new Song( "Purple Rain", 2 );
    songList[1][0] = new Song( "Sing a Song", 1 );
    songList[1][1] = new Song( "Baba O'Riley", 5 );
    songList[1][2] = new Song( "Jumper", 4 );
    songList[1][3] = new Song( "Car Wash", 3 );
    songList[2][0] = new Song( "Kung Fu Fighting", 2 );
    songList[2][1] = new Song( "Right as Rain", 4 );
    songList[2][2] = new Song( "Beat It", 5 );
    songList[2][3] = new Song( "Bust a Move", 4 );

    public  String toString()
    {
        String output = " ";
        for (int row = 0; row < songList.length; row++)
        {
            for (int col = 0; col < songList[row].length; col++)
            {
                output+=(songList[row][col]);
            }
            output += "\n";
        }
        return output;
    }

}

Answer 1

有两个问题

songList需要在放入元素
songList [x] [x]的值应该在构造函数或方法中设置。

public class Jukebox {

    Song[][] songList = new Song[3][4];

    public Jukebox() {
        songList[0][0] = new Song("Jet Airliner", 5);
        songList[0][1] = new Song("Slide", 4);
        songList[0][2] = new Song("Tom Sawyer", 3);
        songList[0][3] = new Song("Purple Rain", 2);
        songList[1][0] = new Song("Sing a Song", 1);
        songList[1][1] = new Song("Baba O'Riley", 5);
        songList[1][2] = new Song("Jumper", 4);
        songList[1][3] = new Song("Car Wash", 3);
        songList[2][0] = new Song("Kung Fu Fighting", 2);
        songList[2][1] = new Song("Right as Rain", 4);
        songList[2][2] = new Song("Beat It", 5);
        songList[2][3] = new Song("Bust a Move", 4);
    }

    public String toString() {
        String output = " ";
        for (int row = 0; row < songList.length; row++) {
            for (int col = 0; col < songList[row].length; col++) {
                output += (songList[row][col]);
            }
            output += "\n";
        }
        return output;
    }
    public static void main(String[] args) {
        Jukebox j = new Jukebox();
    }
}

歌曲

class Song {
    Song(String name, int i) {
    }
}

Answer 2

您需要在方法中执行以下所有操作：

songList[0][0] = new Song("Jet Airliner", 5 );

songList[0][1] = new Song( "Slide", 4 );

songList[0][2] = new Song( "Tom Sawyer", 3 );
songList[0][3] = new Song( "Purple Rain", 2 );
songList[1][0] = new Song( "Sing a Song", 1 );
songList[1][1] = new Song( "Baba O'Riley", 5 );
songList[1][2] = new Song( "Jumper", 4 );
songList[1][3] = new Song( "Car Wash", 3 );
songList[2][0] = new Song( "Kung Fu Fighting", 2 );
songList[2][1] = new Song( "Right as Rain", 4 );
songList[2][2] = new Song( "Beat It", 5 );
songList[2][3] = new Song( "Bust a Move", 4 );

所以你创建一个init()方法，或者如果它适合你的目的就创建一个构造函数。

public void init(){
    songList = new String[3][4];
    songList[0][0] = new Song("Jet Airliner", 5 );

    songList[0][1] = new Song( "Slide", 4 );

    songList[0][2] = new Song( "Tom Sawyer", 3 );
    songList[0][3] = new Song( "Purple Rain", 2 );
    songList[1][0] = new Song( "Sing a Song", 1 );
    songList[1][1] = new Song( "Baba O'Riley", 5 );
    songList[1][2] = new Song( "Jumper", 4 );
    songList[1][3] = new Song( "Car Wash", 3 );
    songList[2][0] = new Song( "Kung Fu Fighting", 2 );
    songList[2][1] = new Song( "Right as Rain", 4 );
    songList[2][2] = new Song( "Beat It", 5 );
    songList[2][3] = new Song( "Bust a Move", 4 );
}

现在，在调用toString()的{{1}}方法之前，您需要调用JukeBox方法。

Answer 3

尝试这个

android:layout_gravity="end"

Answer 4

这个程序在语法上是错误的 1. Song[][] songList;必须由new运营商陪同 2.在实例级别，成员只能在一个语句中初始化。所以下面是错误的：

Song[][] songList;
songList[0][0] = new Song("Jet Airliner", 5 ); 
songList[0][1] = new Song( "Slide", 4 ); 
songList[0][2] = new Song( "Tom Sawyer", 3 ); 
songList[0][3] = new Song( "Purple Rain", 2 ); 
songList[1][0] = new Song( "Sing a Song", 1 ); 
songList[1][1] = new Song( "Baba O'Riley", 5 ); 
songList[1][2] = new Song( "Jumper", 4 ); 
songList[1][3] = new Song( "Car Wash", 3 ); 
songList[2][0] = new Song( "Kung Fu Fighting", 2 ); 
songList[2][1] = new Song( "Right as Rain", 4 ); 
songList[2][2] = new Song( "Beat It", 5 ); 
songList[2][3] = new Song( "Bust a Move", 4 );

解决方案：
1.使用new运算符实例化数组 Song[][] songList = new Song[3][4];

使用初始化程序块或构造函数将对象分配给数组索引。

class Jukebox { Song[][] songList = new Song[3][4]; { //INIT Block for assignments } }
除＃2外，您可以使用数组初始值设定项。

Song[][] songList = new Song[][]{{}{}{}}

Answer 5

在Java中，如果要为类属性赋值，则应在声明它后立即执行。

而不是这样做：

Song[][] songList;

    songList[0][0] = new Song("Jet Airliner", 5 );

    songList[0][1] = new Song( "Slide", 4 );

    songList[0][2] = new Song( "Tom Sawyer", 3 );
    songList[0][3] = new Song( "Purple Rain", 2 );
    songList[1][0] = new Song( "Sing a Song", 1 );
    songList[1][1] = new Song( "Baba O'Riley", 5 );
    songList[1][2] = new Song( "Jumper", 4 );
    songList[1][3] = new Song( "Car Wash", 3 );
    songList[2][0] = new Song( "Kung Fu Fighting", 2 );
    songList[2][1] = new Song( "Right as Rain", 4 );
    songList[2][2] = new Song( "Beat It", 5 );
    songList[2][3] = new Song( "Bust a Move", 4 );

试试这个：

Song[][] songList = {
        {
            new Song("Jet Airliner", 5 ),
            new Song( "Slide", 4 ),
            new Song( "Tom Sawyer", 3 ),
            new Song( "Purple Rain", 2 )
        },
        {
            ...
        }

    };

或者，您可以在构造函数中进行赋值。

public Jukebox(){
songList = {
            {
                new Song("Jet Airliner", 5 ),
                new Song( "Slide", 4 ),
                new Song( "Tom Sawyer", 3 ),
                new Song( "Purple Rain", 2 )
            },
            {
                ...
            }

        };
}

用我的2D数组java代码找不到错误

5 个答案: