📜  将 Long 转换为 String 的Java程序

📅  最后修改于: 2022-05-13 01:55:43.522000             🧑  作者: Mango

将 Long 转换为 String 的Java程序

当我们必须在 GUI 应用程序中显示长数字时,通常需要将 long 类型转换为字符串类型,因为所有内容都以字符串形式显示。

给定一个 Long 数字,任务是在Java中将其转换为 String。

例子:

Input:Long = 20L
Output:"20"

Input:Long = 999999999999L
Output:"999999999999"

A. 使用 +运算符

要将任何数据类型转换为字符串类型,我们可以简单地添加/+ 由双引号(“”)指示的空字符串。

句法:

String str = l+" ";
Java
// Java program to convert Long to String  
// using + operator 
      
public class GFG {  
      
    // main method  
    public static void main(String args[])  
    {  
      
        // create a Long  
        Long varLong = 999999999999L;  
      
        // convert into String 
        String str = varLong+" "; 
        
        // printing the type of str to
        // show that long has been converted to string
        System.out.println("Converted type : "+str.getClass().getName());
      
        // print Long as String  
        System.out.println(str);  
    }  
}


Java
// Java program to convert Long to String
// using valueOf() Method
  
public class GFG {
  
    // main method
    public static void main(String args[])
    {
  
        // create a Long
        Long varLong = 999999999999L;
  
        // convert into String
        String str = String.valueOf(varLong);
  
        // printing the type of str to
        // show that long has been converted to string
        System.out.println("Converted type : "
                           + str.getClass().getName());
  
        // print Long as String
        System.out.println(str);
    }
}


Java
// Java program to convert Long to String  
// using toString() method
      
public class GFG {  
      
    // main method  
    public static void main(String args[])  
    {  
      
        // create a Long  
        Long varLong = 999999999999L;  
      
        // convert into String 
        String str = Long.toString(varLong);  
      
        // printing the type of str to
        // show that long has been converted to string
        System.out.println("Converted type : "
                           + str.getClass().getName());
        
        // print Long as String  
        System.out.println(str);  
    }  
}


Java
// Java program to convert Long to String  
// using long constructer  
   
import java.util.*;
public class GFG {  
      
    // main method  
    public static void main(String args[])  
    {  
      
        // create a Long  
        Long varLong = 999999999999L;  
      
        // convert into String 
        String str = new Long(varLong).toString();  
      
        // printing the type of str to
        // show that long has been converted to string
        System.out.println("Converted type : "
                           + str.getClass().getName());
        
        // print Long as String  
        System.out.println(str);  
    }  
}


Java
// Java program to demonstrate
// working of format() method
  
class Gfg {
    
    public static void main(String args[])
    {
        long varLong = 9999999L;
  
        String str = String.format("%d", varLong);
  
        // printing the type of str to
        // show that long has been converted to string
        System.out.println("Converted type : "
                           + str.getClass().getName());
  
        // print Long as String
        System.out.println(str);
    }
}


Java
// Java program to convert long to
// string using StringBuilder
  
class Gfg {
    public static void main(String args[])
    {
        long varLong = 9999999L;
  
        String str = new StringBuilder().append(varLong).toString();
  
        // printing the type of str to
        // show that long has been converted to string
        System.out.println("Converted type : "
                           + str.getClass().getName());
  
        // print Long as String
        System.out.println(str);
    }
}


输出
Converted type : java.lang.String
999999999999

B. 使用 String.valueOf()

valueOf()方法将数据从其内部形式转换为人类可读的形式。它是一个静态方法,在所有 Java 内置类型的字符串中重载,以便每种类型都可以正确转换为字符串。

当需要某种其他类型数据的字符串表示时调用它 - 例如在连接操作期间。您可以使用任何数据类型调用此方法并获得合理的字符串表示。

句法:

String str = String.valueOf(varLong);

Java

// Java program to convert Long to String
// using valueOf() Method
  
public class GFG {
  
    // main method
    public static void main(String args[])
    {
  
        // create a Long
        Long varLong = 999999999999L;
  
        // convert into String
        String str = String.valueOf(varLong);
  
        // printing the type of str to
        // show that long has been converted to string
        System.out.println("Converted type : "
                           + str.getClass().getName());
  
        // print Long as String
        System.out.println(str);
    }
}
输出
Converted type : java.lang.String
999999999999

C. 使用 Long.toString()

对象类包含 toString() 方法。我们可以使用 toString() 方法来获取对象的字符串表示。每当我们尝试打印对象引用时,就会在内部调用 toString() 方法。如果我们没有在你的类中定义 toString() 方法,那么对象类的 toString() 方法将被调用,否则我们实现/覆盖的 toString() 方法将被调用。

句法:

String str = Long.toString(varLong);

Java

// Java program to convert Long to String  
// using toString() method
      
public class GFG {  
      
    // main method  
    public static void main(String args[])  
    {  
      
        // create a Long  
        Long varLong = 999999999999L;  
      
        // convert into String 
        String str = Long.toString(varLong);  
      
        // printing the type of str to
        // show that long has been converted to string
        System.out.println("Converted type : "
                           + str.getClass().getName());
        
        // print Long as String  
        System.out.println(str);  
    }  
}
输出
Converted type : java.lang.String
999999999999

D.新龙(长升)

这个构造函数在Java 9 中不是 vald。

句法:

String str = new Long(varLong).toString();

Java

// Java program to convert Long to String  
// using long constructer  
   
import java.util.*;
public class GFG {  
      
    // main method  
    public static void main(String args[])  
    {  
      
        // create a Long  
        Long varLong = 999999999999L;  
      
        // convert into String 
        String str = new Long(varLong).toString();  
      
        // printing the type of str to
        // show that long has been converted to string
        System.out.println("Converted type : "
                           + str.getClass().getName());
        
        // print Long as String  
        System.out.println(str);  
    }  
}

由于这个版本的Java不支持这个构造函数。因此,在运行程序时,我们将得到错误显示

Note: prog.java uses or overrides a deprecated API.

E. 使用 String.format()

Java 字符串 format()方法使用给定的语言环境、指定格式字符串参数返回一个格式化字符串

句法:

long varLong = 9999999L;
String str = String.format("%d", varLong);

Java

// Java program to demonstrate
// working of format() method
  
class Gfg {
    
    public static void main(String args[])
    {
        long varLong = 9999999L;
  
        String str = String.format("%d", varLong);
  
        // printing the type of str to
        // show that long has been converted to string
        System.out.println("Converted type : "
                           + str.getClass().getName());
  
        // print Long as String
        System.out.println(str);
    }
}
输出
Converted type : java.lang.String
9999999

F. 使用 StringBuilder、StringBuffer 对象

StringBufferString的对等类,它提供了字符串的大部分功能。字符串表示固定长度的、不可变的字符序列,而 StringBuffer 表示可增长和可写的字符序列。

句法:

long varLong = 9999999L;
String str = new StringBuilder().append(varLong).toString();

Java

// Java program to convert long to
// string using StringBuilder
  
class Gfg {
    public static void main(String args[])
    {
        long varLong = 9999999L;
  
        String str = new StringBuilder().append(varLong).toString();
  
        // printing the type of str to
        // show that long has been converted to string
        System.out.println("Converted type : "
                           + str.getClass().getName());
  
        // print Long as String
        System.out.println(str);
    }
}
输出
Converted type : java.lang.String
9999999