Java Float valueOf() 方法

2025 年 7 月 31 日 | 阅读 2 分钟

Java Float 类的 valueOf() 方法返回一个表示指定浮点值 'f' 或字符串参数 's' 的浮点实例。

语法

1.public static Float valueOf(float f)
2.public  static Float valueOf(String s)

参数

传递 Float 类型 (f) 参数。
传递 String 类型 (s) 参数。

返回值

valueOf() 方法返回指定浮点值或 String 值对应的浮点对象。

示例 1

import java.lang.*;

public class FloatValueOfExample1 {
    public static void main(String[] args) {
        //returns a Float instance
        Float f1 = new Float(48654683);
        System.out.println("1. Value = "+Float.valueOf(f1));
        //passing negative integer
        Float f2 = new Float(-6789.87);
        System.out.println("2. Value = "+Float.valueOf(f2));
        Float f3 = new Float (0.0988767);
        System.out.println("3. Value = "+Float.valueOf(f3));
    }
}

输出

1. Value = 4.8654684E7
2. Value = -6789.87
3. Value = 0.0988767

示例 2

import java.util.Scanner;

public class FloatValueOfExample2 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter your pin code : ");
        String str = scanner.nextLine();
        // valueOF() method for String values
        Float f1 = Float.valueOf(str);
        System.out.println(f1);
        Float f2= 121002.0f;
        Float f3 = 110002.f;
        Float f4 = 201301.0f;
        if (f1.equals(f2)) {
            System.out.println("Area = Faridabad.");
        } else if (f1.equals(f3)) {
            System.out.println("Area = Delhi");
        } else if (f1.equals(f4)) {
            System.out.println("Area = Noida");
        }
        else {
           System.out.println("Sorry! area is out of my knowledge.");
        }
    }
}

输出

Enter your pin code : 121002
121002.0
Area = Faridabad.

示例 3

public class FloatValueOfExample3 {
    public static void main(String[] args) {
        Float f1 = Float.POSITIVE_INFINITY;
        System.out.println("1. Value = "+Float.valueOf(f1));

        Float f2 = Float.NEGATIVE_INFINITY;
        System.out.println("2. Value = "+Float.valueOf(f2));

        Float f3 = Float.MIN_NORMAL;
        System.out.println("3. Value = "+Float.valueOf(f3));

        Float f4 = Float.MAX_VALUE;
        System.out.println("4. Value = "+Float.valueOf(f4));

        Float f5 =Float.MIN_VALUE;
        System.out.println("5. Value = "+Float.valueOf(f5));

        Float f6 =Float.NaN;
        System.out.println("6. Value = "+Float.valueOf(f6));


    }
}

输出

1. Value = Infinity
2. Value = -Infinity
3. Value = 1.17549435E-38
4. Value = 3.4028235E38
5. Value = 1.4E-45
6. Value = NaN

示例 4

import java.util.Scanner;

public class FloatValueOfExample4 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter string value: ");
        String str = scanner.nextLine();
        Float f1 = Float.valueOf(str);
        System.out.println("Float value = "+f1);
    }
}

输出

Enter string value: reema
Exception in thread "main" java.lang.NumberFormatException: For input string: "reema"
	at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:2043)
	at sun.misc.FloatingDecimal.parseFloat(FloatingDecimal.java:122)
	at java.lang.Float.parseFloat(Float.java:451)
	at java.lang.Float.valueOf(Float.java:416)
	at Float_valueOfMethodExample4.main(Float_valueOfMethodExample4.java:8)

它会给我们运行时错误，因为字符串值 reema 无法转换为 Float，因此应该检查此运行时异常。

下一主题Java float longvalue 方法

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Java Float valueOf() 方法

语法

参数

返回值

示例 1

示例 2

示例 3

示例 4

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