如何突破Java中

Question

/出不同水平的方法，通話的

比方說，我有：

public void one() { 
    two(); 
    // continue here 
} 
public void two() { 
    three(); 
} 
public void three() { 
    // exits two() and three() and continues back in one() 
} 

是否有任何方法來這樣做呢？

Answer 1

假設你可以更改two()方法，也許你想像這樣？

public void one() { 
    two(); 
    // continue here from condition 
} 

public void two() { 
    if (three()) { 
     // go back due to condition 
     return; 
    } 

    // condition wasn't met 
} 

public boolean three() { 
    // some condition is determined here 

    if (condition) { 
     // exits two() and three() and continues back in one() 
     return true; 
    } 

    // condition wasn't met, keep processing here 

    // finally return false so two() keeps going too 
    return false; 
} 

Answer 2

沒有改變方法two（）的唯一方法是拋出一個異常。

如果你可以改變代碼，你可以返回一個布爾值，告訴調用者返回。

然而，最簡單的解決方案是將方法內聯到一個更大的方法。如果這太大，你應該重新構建它，而不是像這樣的方法之間放置複雜的控制。

---

說你有

public void one() { 
    System.out.println("Start of one."); 
    two(); 
// do something 
    System.out.println("End of one."); 
} 

public void two() { 
    System.out.println("Start of two."); 
    three(); 
// do something 
    System.out.println("End of two."); 
} 

public void three() { 
    System.out.println("Start of three."); 
// do something 
    System.out.println("End of three."); 
} 

---

您可以添加一個unchecked異常，如果你不能改變兩（）;

public void one() { 
    System.out.println("Start of one."); 
    try { 
     two(); 
    } catch (CancellationException expected) { 
    } 
// do something 
    System.out.println("End of one."); 
} 

public void two() { 
    System.out.println("Start of two."); 
    three(); 
// do something 
    System.out.println("End of two."); 
} 

public void three() { 
    System.out.println("Start of three."); 
// do something 
    System.out.println("End of three."); 
    throw new CancellationException(); // use your own exception if possible. 
} 

---

可以返回一個布爾說回報，如果可以改變兩（）

public void one() { 
    System.out.println("Start of one."); 
    two(); 
// do something 
    System.out.println("End of one."); 
} 

public void two() { 
    System.out.println("Start of two."); 
    if (three()) return; 
// do something 
    System.out.println("End of two."); 
} 

public boolean three() { 
    System.out.println("Start of three."); 
// do something 
    System.out.println("End of three."); 
    return true; 
} 

---

或者你也可以內嵌結構

public void one() { 
    System.out.println("Start of one."); 
    two(); 
// do something 
    System.out.println("End of one."); 
} 

public void two() { 
    System.out.println("Start of two."); 
    System.out.println("Start of three."); 
// do something for three 
    System.out.println("End of three."); 
    boolean condition = true; 
    if (!condition) { 
// do something for two 
     System.out.println("End of two."); 
    } 
} 

Answer 3

展望在你的代碼中，如果你打電話給一個，那麼它會調用兩個，這叫三e .. 如果你保持原樣，那就是它會做的。兩行後（在你的一個）函數，將只會完成一次它從兩個回來，它不會這樣做，直到兩個已完成三個..