如何活动之间传递数据和对数据进行算术运算

Question

我是新来的Android
我已经学会了如何通过putextra传递activites之间的数据，在我的应用程序getextra
，当我从活性1传递数据和活性2到main_activity并添加数据和把它传递给第三活性（输出）
代替此外，只有要么活性1或活性2的值传递给输出正被传递（值被一个我在运行我的应用程序时最后输入的）
这里是我的应用程序的代码
Mainactivity

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

     Intent j = getIntent(); 
     a= j.getDoubleExtra("double1",0.0); 

     Intent k = getIntent(); 
     b = k.getDoubleExtra("double2",0.0); 
     result = a+b; 
    } 


    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.menu_main, menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     // Handle action bar item clicks here. The action bar will 
     // automatically handle clicks on the Home/Up button, so long 
     // as you specify a parent activity in AndroidManifest.xml. 
     int id = item.getItemId(); 

     //noinspection SimplifiableIfStatement 
     if (id == R.id.action_settings) { 
      return true; 
     } 

     return super.onOptionsItemSelected(item); 
    } 

    public void on_click_activity1button(View view) { 
     Intent intent1 = new Intent(this,activity1.class); 
       startActivity(intent1); 

    } 

    public void on_click_activity2button(View view) { 
     Intent intent2 = new Intent(this,activity2.class); 
     startActivity(intent2); 

    } 

    public void on_click_outputbutton(View view) { 
     Intent intent3 = new Intent(this,output.class); 
     intent3.putExtra("result", result); 

     startActivity(intent3); 

    } 
} 

活性1

@Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity1); 
    } 
    public void on_click_activity1done(View view) { 

     EditText text1 = (EditText) findViewById(R.id.activity1edittext); 
     a=Double.parseDouble(text1.getText().toString()); 

     Intent fromactivity1 = new Intent(this,MainActivity.class); 
     fromactivity1.putExtra("double1", a); 
     startActivity(fromactivity1); 
    } 
} 

Activity2.java

@Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity2); 
    } 

    public void on_click_activity2done(View view) { 

     EditText text2 = (EditText) findViewById(R.id.activity2edittext); 
     b=Double.parseDouble(text2.getText().toString()); 

     Intent fromactivity2 = new Intent(this,MainActivity.class); 
     fromactivity2.putExtra("double2", b); 
     startActivity(fromactivity2); 
    } 
} 

output.java

@Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.output); 
     Intent frommaindone = getIntent(); 
     Double total = frommaindone.getDoubleExtra("result",0.0); 
     TextView show = (TextView) findViewById(R.id.resulttextview); 
     show.setText("addition is" + total); 
    } 
} 

请帮助我，并告诉我，我做错了什么

Answer 1

您必须使用startActivityForResult方法从两个输入活动中获取值，然后将结果传递给输出活动。按以下方式更改代码并尝试。

活性1

公共类活性1延伸ActionBarActivity {

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

public void on_click_activity1done(View view) { 

    EditText text1 = (EditText) findViewById(R.id.activity1edittext); 
    double b = Double.parseDouble(text1.getText().toString()); 

    Intent result = new Intent(); 
    result.putExtra("double1", b); 
    setResult(RESULT_OK, result); 
    finish(); 

} 

}

Activity2.java

public class Activity2 extends ActionBarActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity2); 
    } 


    public void on_click_activity2done(View view) { 

     EditText text2 = (EditText) findViewById(R.id.activity2edittext); 
     double b = Double.parseDouble(text2.getText().toString()); 

     Intent result = new Intent(); 
     result.putExtra("double2", b); 
     setResult(RESULT_OK, result); 
     finish(); 

    } 
} 

MainActivity.java

public class MainActivity extends ActionBarActivity { 

    private final int ACTIVITY1 = 1; 
    private final int ACTIVITY2 = 2; 
    private double result, double1,double2; 

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

    } 

    public void onActivityOneClick(View view) { 
     Intent intent = new Intent(this, Activity1.class); 
     startActivityForResult(intent, ACTIVITY1); 
    } 

    public void onActivityTwoClick(View view) { 
     Intent intent = new Intent(this, Activity2.class); 
     startActivityForResult(intent, ACTIVITY2); 
    } 

    public void on_click_outputbutton(View view) { 
     result = double1 + double2; 
     Intent intent = new Intent(this, OutPut.class); 
     intent.putExtra("result", result); 
     startActivity(intent); 
    } 

    @Override 
    protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
     super.onActivityResult(requestCode, resultCode, data); 
     if(resultCode==RESULT_OK){ 
      switch(requestCode){ 
      case ACTIVITY1:  
       double1 = data.getDoubleExtra("double1", 0); 
       break; 
      case ACTIVITY2: 
       double2 = data.getDoubleExtra("double2", 0); 
       break; 
      }     
     } 
    } 
} 

输出。java

public class OutPut extends ActionBarActivity { 

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

     double total = getIntent().getDoubleExtra("result", 0);  
     TextView show = (TextView) findViewById(R.id.resulttextview); 
     show.setText("addition is" + total); 
    } 

} 

Answer 2

这是不可能的，你的代码的工作，因为当你回来，并保存一个值，走出去另一个，你失去了旧的价值。

在我看来，你正在为这个问题做一个坏的方法，但是如果你真的想这样做，我唯一拥有的就是使用静态变量，尽管我不推荐这样做。因此，在MainActivity上创建两个静态变量，保存数据时，在那里执行此操作，并且当您想要输出时，请在两者之间发送操作。这种方式工作。