基本データ型 String型を使う それ以外の方法
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boolean String.valueOf(boolean) new Boolean(boolean).toString()
char String.valueOf(char) new Character(char).toString()
byte String.valueOf(int) Byte.toString(byte)
short String.valueOf(int) Short.toString(short)
int String.valueOf(int) Integer.toString(int)
long String.valueOf(long) Long.toString(long)
float String.valueOf(float) Float.toString(float)
double String.valueOf(double) Double.toString(double)
