Java copy section of array

问题

Is there a method that will copy a section of an array(not arraylist) and make a new array from it?

Example:
[1,2,3,4,5]

and you create a new array from it:

[1,2,3]

Are there any one line/methods that will do this?

回答1:

Here's a java 1.4 compatible 1.5-liner:

int[] array = { 1, 2, 3, 4, 5 };
int size = 3;

int[] part = new int[size];
System.arraycopy(array, 0, part, 0, size);

You could do this in one line, but you wouldn't have a reference to the result.

To make a one-liner, you could refactor this into a method:

private static int[] partArray(int[] array, int size) {
    int[] part = new int[size];
    System.arraycopy(array, 0, part, 0, size);
    return part;
}

then call like this:

int[] part = partArray(array, 3);

回答2:

See the method Arrays.copyOfRange

回答3:

There is a pre-existing method in the java.util.Arrays: newArray = Arrays.copyOfRange(myArray, startindex, endindex). Or you could easily write your own method:

public static array[] copyOfRange(array[] myarray, int from, int to) {
    array[] newarray = new array[to - from];
    for (int i = 0 ; i < to - from ; i++) newarray[i] = myarray[i + from];
    return newarray;
}

回答4:

int [] myArray = [1,2,3,4,5];

int [] holder = new int[size];

System.arraycopy(myArray,0,holder,size);

where 0 stands for the index of source array from where copying should start. and

size stands for the number of copy operations. That you can changes according to your need.

copyOfRange of Arrays is there and many other ways by which this can be accomplished

回答5:

Arrays#copyOfRange does the trick.

回答6:

As others have stated, you can use Arrays.copyOfRange method. An example is :

String[] main = {"one", "two", "three", "four", "five"};
int from = 2;
int to = 4;
String[] part = Arrays.copyOfRange(main, from, to);

Now part will be : {"two", "three", "four"}

来源：https://stackoverflow.com/questions/10423134/java-copy-section-of-array

标签

java

arrays

copy

java1.4