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How to output in java?

青灯夜游

Release： 2019-11-15 14:23:35

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How to output in java?

Two commonly used output methods in java: print() and println(). There is no obvious difference in the input conditions when using these two output methods. The difference is reflected in whether there is a newline at the end of the output. [Recommended learning: java course]

eg:

public class eg {
//交叉使用可以体会到作用的差异
	public static void main(String[] args) {
	System.out.print("123456");
	System.out.println("abced");
	System.out.println("abced");
	System.out.print("123456");
	System.out.println("abced");
 
	}
}

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Result:

How to output in java?

Analysis result: not ugly Out, every time print() is used, the next output (abced) is followed at the end, that is: print() does not wrap. And every time there is a line break after abced.

Note: When using print(), no content output is required

eg:

public class eg {
	public static void main(String[] args) {
	System.out.print();//此时print无内容输出
	}
}

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How to output in java?

## Analysis Result: When using print(), it cannot be compiled when there is no content in the brackets, that is, the program will report an error, so using print() is not allowed.

println() can be output directly and functions as line break

eg:

public class add {
//由于使用单独的一行无法体现结果，所以加入print()显示效果
	public static void main(String[] args) {
        System.out.print("123456");
	System.out.print("123456");
        System.out.println();
	System.out.print("123456");
	}
}

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Result:

How to output in java?

Analysis Result: Among the three lines of print output, only the second output has line breaks, and it is println that provides line breaks for it

print() and println() can be converted to each other, and line breaks can be used \n to perform line breaks, and print() can also achieve the purpose of println()

eg:

public class eg {
//与上图的代码进行对比 效果显而易见
	public static void main(String[] args) {
                System.out.print("123456");
	        System.out.print("123456");
                System.out.print("\n");
	        System.out.print("123456");
	}
}

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Result:

How to output in java?

Result analysis: Obviously, different codes achieve different effects

In addition to the above two common outputs, java also has a powerful output: printf()

Note:

printf() cannot wrap lines
printf() cannot also output directly without content

The output rules of printf() are more like print(), but it has more functions than print(). In C language and C, there is fixed length output, but neither print() nor pritln() in java can implement this function. Java is written in C language, and the fixed-length output function has not been castrated, but has been inherited by printf(). printf's implementation of fixation is similar to C's implementation.

Can output 2, 8, and hexadecimal numbers
Can output in fixed format

The specific implementation is as follows:

package com.hone.test;
 
// "%"表示进行格式化输出， "%"之后的内容为格式的定义。
public class Printf {
    public static void main(String[] args) {
        double d = 345.678;
        String s = "hello World";
        int a = 123;
        
                //浮点型的输出
        System.out.printf("%,d",a);            //格式化输出数据，每三个数据加上一个，
        System.out.println();
        System.out.printf("%f", d);            // 345.678000
        System.out.println();
            //"9.2"中的9表示输出的长度，2表示小数点后的位数。  345.678位数不够前面不上空格
        System.out.printf("%9.3f", d);    
        System.out.println();
        System.out.printf("%+9.3f", d);            //"+"表示输出的数带正负号
        System.out.println();
        System.out.printf("%-9.3f", d);            //"-"表示输出的数左对齐（默认为右对齐）
        System.out.println();
        System.out.printf("%+-9.3f",d);            //"+-"表示输出的数带正负号且左对齐
        System.out.println();
        
                //整型的输出
        System.out.printf("%d", a);                //"d"表示输出十进制整数。
        System.out.println();
        System.out.printf("%04d", a);            //规定为4位，不够左边添加0
        System.out.println();
        System.out.printf("%d%%", a);            //如果想输出百分数，则连续用两个  %%
        System.out.println();
        System.out.printf("%o", a);                //"o"表示输出八进制整数。
        System.out.println();
        System.out.printf("%x", a);                //"x"表示输出八进制整数。
        
        
        //字符串的输出
        System.out.println();
        System.out.printf("%s%n", s);                //输出字符串,其中 %n表示换行
        
        System.out.printf("输出一个浮点数：%.3f,一个整数：%d,一个字符串：%s",d,a,s);        //输出多个变量
        
    }
 
}

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