【java】第1章概述测试题

野性酷女 2022-11-07 04:05 226阅读 0赞

### 文章目录 ###

*   *  1.1 输出
     *  1.2 for循环
     *  1.3
     *  1.4 变量转义字符混合输出
     *  1.5
     *  1.6
     *  1.7
     *  1.8 派的值：Math.PI
     *  1.9 浮点数计算 ？
     *  1.10
     *  1.11 人口估算
     *  1.12 单位换算求平均速度
     *  1.13 解二元二次方程

## 1.1 输出 ##

![在这里插入图片描述][20210310192957524.png]

public class Quiz {
        
    
    	public static void main(String[] args) {
        
    		System.out.println("Welcome to Java");
    		System.out.println("Welcome to Computer Science");
    		System.out.println("Programming is fun");
    	}
    
    }

## 1.2 for循环 ##

![在这里插入图片描述][20210310193221895.png]

public class Quiz {
        
    
    	public static void main(String[] args) {
        
    		for(int i = 0; i < 5; i++) {
        
    			System.out.println("Welcome to Java");
    		}
    	}
    
    }

## 1.3 ##

![在这里插入图片描述][20210310193235522.png]  
![在这里插入图片描述][20210310193244891.png]

public class Quiz {
        
    
    	public static void main(String[] args) {
        
    		System.out.println("    J    A    V     V    A");
    		System.out.println("    J   A A    V   V    A A");
    		System.out.println("J   J  AAAAA    V V    AAAAA");
    		System.out.println(" J J  A     A    V    A     A");
    	}
    
    }

## 1.4 变量转义字符混合输出 ##

![在这里插入图片描述][20210310193258100.png]

public class Quiz {
        
    
    	public static void main(String[] args) {
        
    		System.out.println("a\ta^2\ta^3");
    		for(int a = 1; a <= 4; a++) {
        
    			System.out.println(a + "\t" + a * a + "\t" + a * a * a);
    		}
    	}
    
    }

println就是输出+换行的意思  
如果不用换行用print就行  
\\t是横向制表的tab

## 1.5 ##

![在这里插入图片描述][20210310193400515.png]

public class Quiz {
        
    
    	public static void main(String[] args) {
        
    		System.out.println((9.5 * 4.5 - 2.5 * 3) / (45.5 - 3.5));
    	}
    
    }

## 1.6 ##

![在这里插入图片描述][20210310193448680.png]

public class Quiz {
        
    
    	public static void main(String[] args) {
        
    		int ans = 0;
    		for(int i = 1; i <= 9; i++) {
        
    			ans += i;
    		}
    		System.out.println(ans);
    	}
    
    }

## 1.7 ##

![在这里插入图片描述][20210310193515868.png]

public class Quiz {
        
    
    	public static void main(String[] args) {
        
    		System.out.println(4 * (1.0 - 1.0 / 3 + 1.0 / 5 - 1.0 / 7 + 1.0 / 9 - 1.0 / 11));
    		System.out.println(4 * (1.0 - 1.0 / 3 + 1.0 / 5 - 1.0 / 7 + 1.0 / 9 - 1.0 / 11 + 1.0 /13));
    	}
    
    }

## 1.8 派的值：Math.PI ##

![在这里插入图片描述][2021031019355921.png]

public class Quiz {
        
    
    	public static void main(String[] args) {
        
    		double r = 5.5;
    		double p = Math.PI;
    		System.out.println(2 * r * p);
    		System.out.println(r * r * p);
    	}
    
    }

## 1.9 浮点数计算 ？ ##

![在这里插入图片描述][20210310193613189.png]

public class Quiz {
        
    
    	public static void main(String[] args) {
        
    		System.out.println(4.5 * 7.9);
    		System.out.println(2.0 * (4.5 + 7.9));
    	}
    
    }

4.5 \* 7.9 = 35.550000000000004 ？

## 1.10 ##

![在这里插入图片描述][20210310193701156.png]

public class Quiz {
        
    
    	public static void main(String[] args) {
        
    		System.out.println((14.0 / 1.6) / (45.5 / 60.0));
    	}
    
    }

## 1.11 人口估算 ##

![在这里插入图片描述][20210310193713899.png]

public class Quiz {
        
    
    	public static void main(String[] args) {
        
    		int seconds = 5 * 365 * 24 * 60 * 60;
    		final int current = 312032486;
    		System.out.println(current + seconds / 7.0 - seconds / 13.0 + seconds / 45.0);
    	}
    
    }

## 1.12 单位换算求平均速度 ##

![在这里插入图片描述][20210310193735857.png]

public class Quiz {
        
    
    	public static void main(String[] args) {
        
    		double time = 1 + 40 / 60.0 + 35 / 3600.0;
    		double distance = 24 * 1.6;
    		System.out.println(distance / time);
    	}
    
    }

## 1.13 解二元二次方程 ##

![在这里插入图片描述][20210310193743603.png]

public class Quiz {
        
    
    	public static void main(String[] args) {
        
    		double a, b, c, d, e, f, x, y;
    		a = 3.4;
    		b = 50.2;
    		c = 2.1;
    		d = 0.55;
    		e = 44.5;
    		f = 5.9;
    		x = (e * d - b * f) / (a * d - b * c);
    		y = (a * f - e * c) / (a * d - b * c);
    		System.out.println("x = " + x + ", y = " + y);
    	}
    
    }

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[20210310193221895.png]: /images/20221023/0a61c225a9484534a10a9beab444bc06.png
[20210310193235522.png]: /images/20221023/224fbd1c88e84d1a811c436518edb749.png
[20210310193244891.png]: /images/20221023/bf7c5907c5574427b0a1dbcabf529da9.png
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[20210310193400515.png]: /images/20221023/dcba82d09775435ba23e47cf3c10c09f.png
[20210310193448680.png]: /images/20221023/62b7b1a8d5924032a7dda9465e0fd63d.png
[20210310193515868.png]: /images/20221023/3e1ceb328d7d4453877a54397b44cd13.png
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[20210310193713899.png]: /images/20221023/970a4727d52d4c0d8d98fafa4f03f2ce.png
[20210310193735857.png]: /images/20221023/acaa2138adca43a8863d1ffdbdd5e414.png
[20210310193743603.png]: /images/20221023/145ef78ad8e74934b74d292ef184d353.png