Conversion between String and other data types

Conversion between String and other data types

1. Conversion between String and basic types

1. Convert String to basic data type

For example: Interger.parseInt(String s); this method can convert a string composed of "numeric" characters into integer data.

public class InterviewTest {
    
    
    public static void main(String[] args) {
    
      //注意Character没有parseCharacter方法
        String str = "1234";
        //String类型的数据转换为int类型的数据
        int num1 = Integer.parseInt(str);
        System.out.println(num1);
 
//      String类型的数据转换为Byte类型的数据,注意byte类型值的范围
//      int num2 = Byte.parseByte(str);
//      System.out.println(num2);
//
//      String类型的数据转换为Short类型的数据,注意Short类型所表示的值的范围
//      int num3 = Short.parseShort(str);
//      System.out.println(num3);
 
        //String类型的数据转换为long类型的数据,注意long类型所表示的值的范围
        long num4 = Long.parseLong(str);
        System.out.println(num4);
 
        //String类型的数据转换为float类型的数据,注意float类型所表示的值的范围
        float num5 = Float.parseFloat(str);
        System.out.println(num5);
 
        //String类型的数据转换为double类型的数据,注意double类型所表示的值的范围
        double num6 = Double.parseDouble(str);
        System.out.println(num6);
 
        boolean num7 = Boolean.parseBoolean(str);
        System.out.println(num7);//false
    }

2. Convert basic types into String data

Use the String.valueOf(); method to convert other types of data into string type data.
Note: Char type data cannot be converted.

public class InterviewTest2 {
    
    
   public static void main(String[] args) {
    
    

       //将int类型的数据转换为String类型的数据
       int i = 1234;
       String s1 = String.valueOf(i);
       System.out.println(s1);

       //将float类型的数据转换为String类型的数据
       float f = 0.1f;
       String s2 = String.valueOf(f);
       System.out.println(s2);

       //将boolean类型的数据转换为String类型的数据
       boolean bool = false;
       String s3 = String.valueOf(bool);
       System.out.println(s3);

   }

3. Convert String model data into character array type (char[])

public char[] toCharArray();  

This method stores all the characters of the string in a character array.

public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin);

Provides a method to store strings within a specified index range into an array.

public interface InterviewTest3 {
    
    
    public static void main(String[] args) {
    
    
        String s1 = "abc123";
 
        char[] ch1 = s1.toCharArray();
 
    }

4. Convert character array (char[]) type to String type

Convert through the constructor of the String class.

public class InterviewTest4 {
    public static void main(String[] args) {
        char[] ch = {'a','b','c','1','2','3'};
 
        String s1 = new String(ch);
        System.out.println(s1);
    }

5. Convert String to Byte array

Converted through String's getByte() method.

public class InterviewTest5 {
    public static void main(String[] args) {
        String str = "123abc";
 
        byte[] b = str.getBytes();
 
        for (int i = 0; i <b.length ; i++) {
            System.out.print(b[i]+"\t"); //输出结果为：49	50	51	97	98	99	
                                         //是每个字符对应的ASCⅡ码
        }
    }

6. Convert Byte array to String type

Call the String constructor to implement conversion.

public class InterviewTest6 {
    public static void main(String[] args) {
        byte[] b = {49,50,51,97,98,99};
 
        String s = new String(b);
        System.out.println(s.toString()); //结果为123abc
    }
}