今天突然心血来潮，想看看int与string互转的效率，所以试一下。
1.int转string对比
众所周知，int转string有三种方法：
<pre name="code" class="html">* (1) String.valueOf(i) * (2) Integer.toString(i) * (3) i + ""下面是对比：
public class TestInt2String {
public static void main(String[] args) {
int[] intArr = new int[1000000];
String[] strArr1 = new String[1000000];// 为了公平分别定义三个数组
String[] strArr2 = new String[1000000];
String[] strArr3 = new String[1000000];
// 赋值
Long t1 = System.nanoTime();
for (int i = 0; i < 1000000; i++) {
intArr[i] = i + 1;
}
Long t2 = System.nanoTime();
for (int i = 0; i < 1000000; i++) {
strArr1[i] = String.valueOf(intArr[i]);
}
Long t3 = System.nanoTime();
for (int i = 0; i < 1000000; i++) {
strArr2[i] = Integer.toString(intArr[i]);
}
Long t4 = System.nanoTime();
for (int i = 0; i < 1000000; i++) {
strArr3[i] = intArr[i] + "";
}
Long t5 = System.nanoTime();
System.out.println("t1 = " + t1);
System.out.println("t2 = " + t2);
System.out.println("t3 = " + t3);
System.out.println("t4 = " + t4);
System.out.println("t5 = " + t5);
System.out.println("赋值：" + (t2 - t1)/1e6);
System.out.println("String.valueOf(i)：" + (t3 - t2)/1e6);
System.out.println("Integer.toString(i)：" + (t4 - t3)/1e6);
System.out.println("i+\"\"：" + (t5 - t4)/1e6);
}
}
结果如下：
t1 = 19060665491808 t2 = 19060671491829 t3 = 19060801637489 t4 = 19060834225943 t5 = 19061039822991 赋值：6.000021 String.valueOf(i)：130.14566 Integer.toString(i)：32.588454 i+""：205.597048
可以看出来，Integer.toString是最快的。
2.string转int对比
string转int
* (1) Integer.parseInt(str) * (2) Integer.valueOf(s).intValue()下面是对比：
public static void main(String[] args) {
String[] strArr = new String[1000000];
int[] intArr1 = new int[1000000];// 为了公平分别定义三个数组
int[] intArr2 = new int[1000000];
int[] intArr3 = new int[1000000];
// 赋值
Long t1 = System.nanoTime();
for (int i = 0; i < 1000000; i++) {
strArr[i] = Integer.toString(i + 1);
}
Long t2 = System.nanoTime();
for (int i = 0; i < 1000000; i++) {
intArr1[i] = Integer.parseInt(strArr[i]);
}
Long t3 = System.nanoTime();
for (int i = 0; i < 1000000; i++) {
intArr2[i] = Integer.valueOf(strArr[i]);
}
Long t4 = System.nanoTime();
for (int i=0;i<1000000;i++){
intArr3[i] = Integer.valueOf(strArr[i]).intValue();
}
Long t5 = System.nanoTime();
System.out.println("t1 = " + t1);
System.out.println("t2 = " + t2);
System.out.println("t3 = " + t3);
System.out.println("t4 = " + t4);
System.out.println("t5 = " + t5);
System.out.println("赋值：" + (t2 - t1) / 1e6);
System.out.println("Integer.parseInt(s)：" + (t3 - t2) / 1e6);
System.out.println("Integer.valueOf：" + (t4 - t3) / 1e6);
System.out.println("Integer.valueOf(s).intValue()" + (t5 - t4) / 1e6);
}
结果如下：
t1 = 20125416119650 t2 = 20125513532523 t3 = 20125542724055 t4 = 20125569908737 t5 = 20125596152378 赋值：97.412873 Integer.parseInt(s)：29.191532 Integer.valueOf：27.184682 Integer.valueOf(s).intValue()26.243641可以看出，基本上相同。
