Conversion between basic data types, packaging classes and String types

//基本数据类型、包装类——》String类型
	@Test
	public void test4(){
		int num1 = 100;
		//方式一：链接运算
		String str1 = num1 + "";
		System.out.println(str1);
		//方式二
		//调用String重载的valueOf(Xxx xxx)
		float f1 = 12.3f;
		String str2 = String.valueOf(f1);
		System.out.println(str2);  //"12.3"
		Double d1 = new Double(66.6);
		String str3 = String.valueOf(d1);
		System.out.println(str3);
	}

 

//String类型——》基本数据类型、包装类
	@Test
	public void test5(){
		String str1 = "123";
		/*
		 * 错误的情况
		 * int num1 = (int)str1;
		 * Integer in1 = (Integer)str1;
		 * */
		//调用包装类的方法：parseXxx(String s)
		int num1 = Integer.parseInt(str1);
		System.out.println(num1);
		
		String str2 = "truE";
		boolean b1 = Boolean.parseBoolean(str2);
		System.out.println(b1);  //true
	}