double?m?=?78.5; //將基本類型轉換為字符串 //String?str1?=?Double.toString(m); ????????//String?str1?=?String.valueOf(m); ????????String?str1?=?""+m; ???????? /*System.out.println("m?轉換為String型后與整數20的求和結果為：?"+(Double.parseDouble(str1)+20));*/ ????????/*System.out.println("m?轉換為String型后與整數20的求和結果為：?"+((double)Double.valueOf(str1)+20));*/ System.out.println("m?轉換為String型后與整數20的求和結果為：?"+(Double.valueOf(str1).doubleValue()+20)); ???????? String?str?=?"180.20"; ????//?將字符串轉換為基本類型 //Double?a?=?Double.valueOf(str); ????????//Double?a?=(Double)Double.parseDouble(str); ????????Double?a?=new?Double(Double.parseDouble(str)); System.out.println("str?轉換為double型后與整數20的求和結果為：?"+(a+20));