Float四捨五入保留一位小數點

public class Test {
    public static void main(String[] args){
        double data1 = 3.35;
        float data2 = 3.35f
 
;
        System.out.println(String.format("%.1f", data1));//輸出3.4 進行四捨五入小數點
        System.out.println(String.format("%.1f", data2));//輸出3.3
        // 強轉float為double型別 部分會失真
 

        System.out.println((double)(data2));//輸出3.3499999046325684  所以會導致 第二結果為3.3

        System.out.print(strOnePointOfFloat(5.54f)); // output 5.5
        System.out.print(strOnePointOfFloat(5.56f
 
)); // output 5.6
    }

    public static String strOnePointOfFloat(float f){
        return String.format("%.1f", Double.valueOf(String.valueOf(f)));
    }
}