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Copy pathStringPractice.java
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72 lines (64 loc) · 2.29 KB
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/**
String,StringBuffer,StringBuilder测试
具体区别在java-study中
* */
public class StringPractice {
private static int time = 50000;
public static void main(String[] args) {
testString();
testStringBuffer();
testStringBuilder();
test1String();
test2String();
}
/**
“对String对象的任何改变都不影响到原对象，相关的任何change操作都会生成新的对象”。
* */
public static void testString () {
String s="";
long begin = System.currentTimeMillis();
for(int i=0; i<time; i++){
s += "java";
}
long over = System.currentTimeMillis();
System.out.println("操作"+s.getClass().getName()+"类型使用的时间为："+(over-begin)+"毫秒");
}
public static void testStringBuffer () {
StringBuffer sb = new StringBuffer();
long begin = System.currentTimeMillis();
for(int i=0; i<time; i++){
sb.append("java");
}
long over = System.currentTimeMillis();
System.out.println("操作"+sb.getClass().getName()+"类型使用的时间为："+(over-begin)+"毫秒");
}
public static void testStringBuilder () {
StringBuilder sb = new StringBuilder();
long begin = System.currentTimeMillis();
for(int i=0; i<time; i++){
sb.append("java");
}
long over = System.currentTimeMillis();
System.out.println("操作"+sb.getClass().getName()+"类型使用的时间为："+(over-begin)+"毫秒");
}
public static void test1String () {
//"I"+"love"+"java"在编译期间会被优化成"ilovejava"
long begin = System.currentTimeMillis();
for(int i=0; i<time; i++){
String s = "I"+"love"+"java";
}
long over = System.currentTimeMillis();
System.out.println("字符串直接相加操作："+(over-begin)+"毫秒");
}
public static void test2String () {
String s1 ="I";
String s2 = "love";
String s3 = "java";
long begin = System.currentTimeMillis();
for(int i=0; i<time; i++){
String s = s1+s2+s3;
}
long over = System.currentTimeMillis();
System.out.println("字符串间接相加操作："+(over-begin)+"毫秒");
}
}