代码如下
public static void main(String[] args) {
Random random = new Random(); int[] vs = new int[100000];
for (int i = 0; i < vs.length; i++) {
vs[i] = random.nextInt();
} int[] vs2 = new int[100000];
long t0 = System.currentTimeMillis();
for (int i = 0; i < 10000; i++) { System.arraycopy(vs, 0, vs2, 0, vs.length);
}
System.out.println(System.currentTimeMillis() - t0); t0 = System.currentTimeMillis();
for (int i = 0; i < 10000; i++) {
for (int k = 0; k < vs.length; k++) {
vs2[k] = vs[k];
}
}
System.out.println(System.currentTimeMillis() - t0); }执行结果:
399
356
public static void main(String[] args) {
Random random = new Random(); int[] vs = new int[100000];
for (int i = 0; i < vs.length; i++) {
vs[i] = random.nextInt();
} int[] vs2 = new int[100000];
long t0 = System.currentTimeMillis();
for (int i = 0; i < 10000; i++) { System.arraycopy(vs, 0, vs2, 0, vs.length);
}
System.out.println(System.currentTimeMillis() - t0); t0 = System.currentTimeMillis();
for (int i = 0; i < 10000; i++) {
for (int k = 0; k < vs.length; k++) {
vs2[k] = vs[k];
}
}
System.out.println(System.currentTimeMillis() - t0); }执行结果:
399
356
for (int i = 0; i < 10000; i++) {
for (int k = 0; k < vs.length; k++) {
vs2[k] = vs[k];
}
}
复制数组,为什么里面又嵌套了一个循环,有什么作用么?没看懂
System.arraycopy(vs, 0, vs2, 0, vs.length);
}vs2要在前面吧,不用for循环都行