java 字符串（String）基本用法

String str = "strExample";

1. 判断字符串与另一字符串是否相等

if(str.equals("strExample")) {

}

2.判断字符串开头

if (str_receive.startsWith("str")) {

}

3.截掉字符串前半段

String Name = str.substring(4);//结果是：Example

4.按照位置截取字符串

str.substring(2,5);

5.字符串转16进制

byte[] byteArray = str.getBytes();

6.指定分隔符切割字符串

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String string = "255:255:88:88";
String[] ARGB = string.split(":");//ARGB = {255,255,88,88}

7.字符串转int

int i = Integer.parseInt("3");

8.int(char\long\float\double\char[]\bool)转字符串

String string = String.valueOf(9);

9.连接字符串

//连接字符串
StringBuilder result = new StringBuilder();
for (int i=0;i<strList.size();i++) {
    String str = strList.get(i);
    result.append(str).append(":");
}

10. 删除字符串最后的字符

str.substring(0,str.length()-1);

11. 将16进制字符串转成byte[]

/**
 * 将16进制字符串(例如"3E 43 4F")转换为byte[]
 */
public static byte[] strToBytes(String str) {
    if(str == null || str.trim().equals("")) {
        return new byte[0];
    }
    
    //去除字符串中的空格转成数组
    String[] array16 = str.split(" ");
    //数组转字符串有,隔开: {3E,43,4F}
    String str16 = Arrays.toString(array16);
    //数组转字符串无,隔开：3E434F
    StringBuilder build = new StringBuilder();
    for (int i = 0; i < array16.length; i++) {
        build.append(array16[i]);
    }
    
    byte[] bytes = new byte[build.length() / 2];
    for(int i = 0; i < build.length() / 2; i++) {
        String subStr = build.substring(i * 2, i * 2 + 2);
        bytes[i] = (byte) Integer.parseInt(subStr, 16);
    }
    
    return bytes;
}