The article directories

  • 1. Basic data type and String type conversion
    • 1.1 Introduction and Usage
    • 1.2 Precautions

1. Basic data type and String type conversion

1.1 Introduction and Usage

  • Case: StringToBasic. Java
	// Basic data type ->String
	
	int n1 = 100;
	float f1 = 1.1 F;
	double d1 = 4.5;
	boolean b1 = true;
	String s1 = n1 + "";
	String s2 = f1 + "";
	String s3 = d1 + "";
	String s4 = b1 + "";
	System.out.println(s1 + "" + s2 + "" + s3 + "" + s4);
	
	//String-> The corresponding basic data type
	String s5 = "123";
	// We'll go into more detail when OOP talks about objects and methods
	// Read the corresponding method of the wrapper class that uses the basic datatype to get the basic datatype
	int num1 = Integer.parseInt(s5);
	double num2 = Double.parseDouble(s5);
	float num3 = Float.parseFloat(s5);
	long num4 = Long.parseLong(s5);
	byte num5 = Byte.parseByte(s5);
	boolean b = Boolean.parseBoolean("true");
	short num6 = Short.parseShort(s5);
	
	System.out.println("= = = = = = = = = = = = = = = = = = =");
	System.out.println(num1);/ / 123
	System.out.println(num2);/ / 123.0
	System.out.println(num3);/ / 123.0
	System.out.println(num4);/ / 123
	System.out.println(num5);/ / 123
	System.out.println(num6);/ / 123
	System.out.println(b);//true
	
	// How to convert a string to a character char -
	// read s5.charAt(0) to get the first character of s5 string '1'
	System.out.println(s5.charAt(0));
Copy the code

1.2 Precautions

  • Case: StringToBasicDetail. Java
	String str = "hello";
	/ / to int
	int n1 = Integer.parseInt(str);
	System.out.println(n1);
Copy the code