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CodeGym/Adesua ahorow/Java 語法/級聯

級聯

Java 語法
等級 3, 課堂 5
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“我想告訴你如何合併字符串。合併或連接字符串的過程通常使用簡稱“連接”來表示。貓愛好者會發現它很容易記住：con-Cat-en-Nation。我開玩笑的。

“合併字符串的規則很簡單。如果我們‘添加’(+) 一個字符串和其他東西，那麼‘其他’會通過 toString() 方法隱式轉換為字符串。 ”

“你剛才是在跟我說話嗎？”

“好吧，我會用更簡單的方式解釋它。如果我們添加一個字符串，一個數字和一隻貓，那麼數字和貓都會被轉換為字符串。這裡有一些例子：”

代碼 等效代碼 
Cat cat = new Cat();
String text = "The cat is " + cat;
 Cat cat = new Cat();
String s = cat.toString();
String text = "The cat is " + s;		 
int a = 5;
String text = "a is " + a;
 int a = 5;
String s = Integer.toString(a);
String text = "a is " + s;		 
int a = 5;
String text = a + "a is ";
 int a = 5;
String s = Integer.toString(a);
String text = s + "a is ";		 
Cat cat = new Cat();
int a = 5;
String text = "The cat is " + cat + a;
 Cat cat = new Cat();
String s1 = cat.toString();
String s2 = Integer.toString(a);
String text = "The cat is " + s1 + s2;		 
Cat cat = new Cat();
int a = 5;
String text = a + "The cat is " + cat + a;
 Cat cat = new Cat();
String s1 = cat.toString();
String s2 = Integer.toString(a);
String s3 = Integer.toString(a);
String text = s3 + "The cat is " + s1 + s2;		 
Cat cat = new Cat();
int a = 5;
String text = cat + a + "The cat is " + cat + a;
 該程序將無法編譯！
加法運算是從左到右執行的，所以我們得到：如果我們給一個數字加上一隻貓，沒有自動的字符串轉換。
String text = (((cat + a) + "The cat is ") + cat) + a;
 
// But you can do this:
Cat cat = new Cat();
int a = 5;
String text = cat + (a + "The cat is ") + cat + a;

// This is the same as:
Cat cat = new Cat();
int a = 5;
String text = ((cat + (a + "The cat is ")) + cat)+a;
 Cat cat = new Cat();
String s1 = cat.toString();
String s2 = cat.toString();
String s3 = Integer.toString(a);
String s4 = Integer.toString(a);
String text = s1 + s3 + "The cat is " + s2 + s4;

“是時候從迭戈那裡完成一些任務了。”

1
任務
Java 語法,  等級 3,  課堂 5
上鎖
Fill a pool with water
Today our task is to fill a pool with water. In doing so, we mustn't drown anyone, but we also don't want to hold back: we'll fill it to the brim! The filling method will take the dimensions of the pool. We will assume that it is a parallelepiped, i.e. it has a well-defined length, width and depth. And the method will return the required amount of water. In liters.
1
任務
Java 語法,  等級 3,  課堂 5
上鎖
Printing strings
I foresee a recurring need to print strings in the life of a programmer! To print a string, you have to use a specific method... or write your own that has some special features. This task is different in that our method shouldn't simply display a string. Instead, it should change the string by adding the word "printing".
3
任務
Java 語法,  等級 3,  課堂 5
上鎖
Time conversion
Hours are few, but seconds are many. Perhaps measuring time in seconds would give the illusion that we have more time than we really do? Anyway, enough philosophizing. Let's work on programming. We need to implement a method that will convert hours to seconds, and then we'll see what this gets us.
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