如何在 Java 中表示二维矩阵？
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How to represent a 2D matrix in Java?
提问by machinery
I have to create in Java a 2D matrix (consisting of double values) as well as a 1D vector. It should be possible to access individual rows and columns as well as individual elements. Moreover, it should be thread-safe (threads writing at the same time). Perhaps later I need some matrix operations too.
我必须在 Java 中创建一个 2D 矩阵（由双值组成）以及一个 1D 向量。应该可以访问单个行和列以及单个元素。此外，它应该是线程安全的（线程同时写入）。也许以后我也需要一些矩阵运算。
Which data structure is best for this? Just a 2D array or a TreeMap? Or is there any amazing external library?
哪种数据结构最适合这个？只是一个二维数组还是一个 TreeMap？或者有什么惊人的外部库？
采纳答案by Noor Nawaz
You should use Vector for 2D array. It is threadsafe.
您应该将 Vector 用于二维数组。它是线程安全的。
Vector<Vector<Double>> matrix= new Vector<Vector<Double>>();
for(int i=0;i<2;i++){
Vector<Double> r=new Vector<>();
for(int j=0;j<2;j++){
r.add(Math.random());
}
matrix.add(r);
}
for(int i=0;i<2;i++){
Vector<Double> r=matrix.get(i);
for(int j=0;j<2;j++){
System.out.print(r.get(j));
}
System.out.println();
}
If this is your matrix indexes
如果这是您的矩阵索引
00 01
00 01
10 11
10 11
You can get specifix index value like this
您可以像这样获得特定的索引值
Double r2c1=matrix.get(1).get(0); //2nd row 1st column
Have a look at Vector
看看 向量
回答by Paulo
I'll give you an example:
我给你举个例子：
int rowLen = 10, colLen = 20;
Integer[][] matrix = new Integer[rowLen][colLen];
for(int i = 0; i < rowLen; i++)
for(int j = 0; j < colLen; j++)
matrix[i][j] = 2*(i + j); // only an example of how to access it. you can do here whatever you want.
Clear?
清除？
回答by Aniket Rangrej
If you need thread safe behavior, use
如果您需要线程安全行为，请使用
Vector<Vector<Double>> matrix = new Vector<Vector<Double>>();
If you don't need thread safe behavior, use
如果您不需要线程安全行为，请使用
ArrayList<ArrayList<Double>> matrix = new ArrayList<ArrayList<Double>>();
