錯誤鑄造

Question

我創建的其他類的全局變量的一類，現在我只想投它這樣的：

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity1); 
    class2 global; 

    global = (class2)getApplicationContext(); 

我得到錯誤：

android.app.Application cannot be cast to eu.tools.test_training_home.class2

的class2：

public class class2 extends Application { 

    private String name="name1"; 
    private int number =0; 

Answer 1

這裏getApplicationContext()返回類Context的對象，但不是class2 。

檢查https://stackoverflow.com/a/907368/1435132。

見Custom global Application class breaks with "android.app.Application cannot be cast to"

Answer 2

問題是Consructor在Class2中 到Class2中，我有1個constuctor，2二傳手，2吸氣 我刪除了構造函數，則誤差不來

public class class2 extends Application { 

private String name ="name1"; 
private int number =10; 

public class2(String name, int number) { // this was the problem 
    this.name = name; 
    this.number = number; 
} 

public void setName(String name) { 
    this.name = name; 
} 

public void setNumber(int number) { 
    this.number = number; 
} 

public String getName() { 
    return name; 
} 

public int getNumber() { 
    return number; 
} 

}