blocks|key|554535|text|使用Java的Float类。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|554536|float+f+=+Float.parseFloat("25");
String+s+=+Float.toString(25.0f);|code-block|syntax|javascript|554537|为了进行比较，最好将字符串转换为浮点型，并将其作为两个浮点型进行比较。这是因为对于一个浮点数，有多个字符串表示，当与字符串进行比较时，它们是不同的(例如，"25“!=+"25.0”!=+"25.00“等)。|554538|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.oracle.com/javase/8/docs/api/java/lang/Float.html^0|7|5|7|5|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@$9|X|A|Y|1|Z]]|E|$]]|$1|F|3|G|5|H|7|10|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|11|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

Using Java’s <a href="https://docs.oracle.com/javase/8/docs/api/java/lang/Float.html" rel="noreferrer"><code>Float</code></a> class.

<pre><code>float f = Float.parseFloat("25");
String s = Float.toString(25.0f);
</code></pre>

To compare it's always better to convert the string to float and compare as two floats. This is because for one float number there are multiple string representations, which are different when compared as strings (e.g. "25" != "25.0" != "25.00" etc.)

blocks|key|771173|text|Float+to+string+-+String.valueOf()|type|unstyled|depth|inlineStyleRanges|entityRanges|data|771174|float+amount=100.00f;
String+strAmount=String.valueOf(amount);
//+or++Float.toString(float)|code-block|syntax|javascript|771175|Float+-+Float.parseFloat()的字符串|771176|String+strAmount="100.20";
float+amount=Float.parseFloat(strAmount)
//+or++Float.valueOf(string)|771177|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Float to string - String.valueOf()

<pre><code>float amount=100.00f;
String strAmount=String.valueOf(amount);
// or Float.toString(float)
</code></pre>

String to Float - Float.parseFloat()

<pre><code>String strAmount="100.20";
float amount=Float.parseFloat(strAmount)
// or Float.valueOf(string)
</code></pre>

blocks|key|554586|text|您可以尝试以下代码示例：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|554587|public+class+StringToFloat
{

++public+static+void+main+(String[]+args)
++{

++++//+String+s+=+"fred";++++//+do+this+if+you+want+an+exception

++++String+s+=+"100.00";

++++try
++++{
++++++float+f+=+Float.valueOf(s.trim()).floatValue();
++++++System.out.println("float+f+=+"+%2B+f);
++++}
++++catch+(NumberFormatException+nfe)
++++{
++++++System.out.println("NumberFormatException:+"+%2B+nfe.getMessage());
++++}
++}
}|code-block|syntax|javascript|554588|找到here|offset|length|554589|entityMap|0|LINK|mutability|MUTABLE|url|http://www.devdaily.com/java/edu/qanda/pjqa00013.shtml^0|0|0|2|4|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

You can try this sample of code:

<pre><code>public class StringToFloat
{

 public static void main (String[] args)
 {

 // String s = "fred"; // do this if you want an exception

 String s = "100.00";

 try
 {
 float f = Float.valueOf(s.trim()).floatValue();
 System.out.println("float f = " + f);
 }
 catch (NumberFormatException nfe)
 {
 System.out.println("NumberFormatException: " + nfe.getMessage());
 }
 }
}
</code></pre>

found <a href="http://www.devdaily.com/java/edu/qanda/pjqa00013.shtml" rel="noreferrer">here</a>

blocks|key|771221|text|我相信下面的代码会有所帮助：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|771222|float+f1+=+1.23f;
String+f1Str+=+Float.toString(f1);++++++
float+f2+=+Float.parseFloat(f1Str);|code-block|syntax|javascript|771223|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I believe the following code will help:

<pre><code>float f1 = 1.23f;
String f1Str = Float.toString(f1); 
float f2 = Float.parseFloat(f1Str);
</code></pre>

blocks|key|554834|text|如果你在找，比如两位小数..Float+f+=+(float)12.34;+++++String+s+=+new+DecimalFormat+("#.00").format+(f);|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|554835|entityMap^0|E|25|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

If you're looking for, say two decimal places..
 <code>
 Float f = (float)12.34;
 String s = new DecimalFormat ("#.00").format (f);
</code>

blocks|key|771294|text|这个方法不是很好，但很简单，不建议使用。也许我应该说这是最低效的方法和最糟糕的编码实践，但是，使用起来很有趣。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|771295|float+val=10.0;
String+str=val%2B"";|code-block|syntax|javascript|771296|空引号，向变量str添加一个空字符串，将'val‘向上转换为字符串类型。|771297|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

well this method is not a good one, but easy and not suggested. Maybe i should say this is the least effective method and the worse coding practice but, fun to use,

<pre><code>float val=10.0;
String str=val+"";
</code></pre>

the empty quotes, add a null string to the variable str, upcasting 'val' to the string type.

blocks|key|771318|text|String+str+=+"1234.56";
float+num+=+0.0f;

int+digits+=+str.length()-+str.indexOf('.')+-+1;

float+factor+=+1f;

for(int+i=0;i<digits;i%2B%2B)+factor+/=+10;

for(int+i=str.length()-1;i>=0;i--){

++++if(str.charAt(i)+==+'.'){
++++++++factor+=+1;
++++++++System.out.println("Reset,+value="%2Bnum);
++++++++continue;
++++}

++++num+%2B=+(str.charAt(i)+-+'0')+*+factor;
++++factor+*=+10;
}

System.out.println(num);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|771319|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>String str = "1234.56";
float num = 0.0f;

int digits = str.length()- str.indexOf('.') - 1;

float factor = 1f;

for(int i=0;i&lt;digits;i++) factor /= 10;

for(int i=str.length()-1;i&gt;=0;i--){

 if(str.charAt(i) == '.'){
 factor = 1;
 System.out.println("Reset, value="+num);
 continue;
 }

 num += (str.charAt(i) - '0') * factor;
 factor *= 10;
}

System.out.println(num);
</code></pre>

blocks|key|554929|text|完全手动执行:此方法通过移动数字的小数点并使用floor+(to+long)和modulus来提取数字，从而将双精度数转换为字符串。此外，它使用基数除法计数来计算小数点所属的位置。一旦数字到达小数点后的位置，它还可以“删除”数字的较高部分，以避免在超大双精度情况下失去精度。请参阅末尾的注释代码。在我的测试中，当Java+float表示实际上显示这些不精确的小数位时，它的精度永远不会低于Java+float表示本身。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|554930|/**
+*+Convert+the+given+double+to+a+full+string+representation,+i.e.+no+scientific+notation
+*+and+always+twelve+digits+after+the+decimal+point.
+*+@param+d+The+double+to+be+converted
+*+@return+A+full+string+representation
+*/
public+static+String+fullDoubleToString(final+double+d)+{
++++//+treat+0+separately,+it+will+cause+problems+on+the+below+algorithm
++++if+(d+==+0)+{
++++++++return+"0.000000000000";
++++}
++++//+find+the+number+of+digits+above+the+decimal+point
++++double+testD+=+Math.abs(d);
++++int+digitsBeforePoint+=+0;
++++while+(testD+>=+1)+{
++++++++//+doesn't+matter+that+this+loses+precision+on+the+lower+end
++++++++testD+/=+10d;
++++++++%2B%2BdigitsBeforePoint;
++++}

++++//+create+the+decimal+digits
++++StringBuilder+repr+=+new+StringBuilder();
++++//+10%5E+exponent+to+determine+divisor+and+current+decimal+place
++++int+digitIndex+=+digitsBeforePoint;
++++double+dabs+=+Math.abs(d);
++++while+(digitIndex+>+0)+{
++++++++//+Recieves+digit+at+current+power+of+ten+(=+place+in+decimal+number)
++++++++long+digit+=+(long)Math.floor(dabs+/+Math.pow(10,+digitIndex-1))+%25+10;
++++++++repr.append(digit);
++++++++--digitIndex;
++++}

++++//+insert+decimal+point
++++if+(digitIndex+==+0)+{
++++++++repr.append(".");
++++}

++++//+remove+any+parts+above+the+decimal+point,+they+create+accuracy+problems
++++long+digit+=+0;
++++dabs+-=+(long)Math.floor(dabs);
++++//+Because+of+inaccuracy,+move+to+entirely+new+system+of+computing+digits+after+decimal+place.
++++while+(digitIndex+>+-12)+{
++++++++//+Shift+decimal+point+one+step+to+the+right
++++++++dabs+*=+10d;
++++++++final+var+oldDigit+=+digit;
++++++++digit+=+(long)Math.floor(dabs)+%25+10;
++++++++repr.append(digit);

++++++++//+This+may+avoid+float+inaccuracy+at+the+very+last+decimal+places.
++++++++//+However,+in+practice,+inaccuracy+is+still+as+high+as+even+Java+itself+reports.
++++++++//+dabs+-=+oldDigit+*+10l;
++++++++--digitIndex;
++++}

++++return+repr.insert(0,+d+<+0+?+"-"+:+"").toString();+
}|code-block|syntax|javascript|554931|请注意，虽然StringBuilder用于提高速度，但这种方法可以很容易地重写为使用数组，因此也可以在其他语言中使用。|554932|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

To go the full manual route: This method converts doubles to strings by shifting the number's decimal point around and using floor (to long) and modulus to extract the digits. Also, it uses counting by base division to figure out the place where the decimal point belongs. It can also &quot;delete&quot; higher parts of the number once it reaches the places after the decimal point, to avoid losing precision with ultra-large doubles. See commented code at the end. In my testing, it is never less precise than the Java float representations themselves, when they actually show these imprecise lower decimal places.
<pre><code>/**
 * Convert the given double to a full string representation, i.e. no scientific notation
 * and always twelve digits after the decimal point.
 * @param d The double to be converted
 * @return A full string representation
 */
public static String fullDoubleToString(final double d) {
 // treat 0 separately, it will cause problems on the below algorithm
 if (d == 0) {
 return &quot;0.000000000000&quot;;
 }
 // find the number of digits above the decimal point
 double testD = Math.abs(d);
 int digitsBeforePoint = 0;
 while (testD &gt;= 1) {
 // doesn't matter that this loses precision on the lower end
 testD /= 10d;
 ++digitsBeforePoint;
 }

 // create the decimal digits
 StringBuilder repr = new StringBuilder();
 // 10^ exponent to determine divisor and current decimal place
 int digitIndex = digitsBeforePoint;
 double dabs = Math.abs(d);
 while (digitIndex &gt; 0) {
 // Recieves digit at current power of ten (= place in decimal number)
 long digit = (long)Math.floor(dabs / Math.pow(10, digitIndex-1)) % 10;
 repr.append(digit);
 --digitIndex;
 }

 // insert decimal point
 if (digitIndex == 0) {
 repr.append(&quot;.&quot;);
 }

 // remove any parts above the decimal point, they create accuracy problems
 long digit = 0;
 dabs -= (long)Math.floor(dabs);
 // Because of inaccuracy, move to entirely new system of computing digits after decimal place.
 while (digitIndex &gt; -12) {
 // Shift decimal point one step to the right
 dabs *= 10d;
 final var oldDigit = digit;
 digit = (long)Math.floor(dabs) % 10;
 repr.append(digit);

 // This may avoid float inaccuracy at the very last decimal places.
 // However, in practice, inaccuracy is still as high as even Java itself reports.
 // dabs -= oldDigit * 10l;
 --digitIndex;
 }

 return repr.insert(0, d &lt; 0 ? &quot;-&quot; : &quot;&quot;).toString(); 
}
</code></pre>
Note that while StringBuilder is used for speed, this method can easily be rewritten to use arrays and therefore also work in other languages.

How could I convert from float to string or string to float?

In my case I need to make the assertion between 2 values string (value that I have got from table) and float value that I have calculated.

<pre><code>String valueFromTable = "25";
Float valueCalculated =25.0;
</code></pre>

I tried from float to string:

<pre><code>String sSelectivityRate = String.valueOf(valueCalculated );
</code></pre>

but the assertion fails

java : convert float to String and String to float

如何将float转换为字符串或将字符串转换为float？在我的例子中，我需要在两个值字符串(我从表中获得的值)和我计算出的浮点值之间进行断言。String valueFromTable = "25";Float valueCalculated =25.0;我试着从浮动到字符串：String sSelectivityRate = String.valueOf(valueCalculated );但是

问java :将float转换为String，将String转换为float
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回答 8

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问java :将float转换为String，将String转换为floatEN

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问java :将float转换为String，将String转换为float
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