Android屏幕間的跳轉和事件的傳遞

在一般情況下，Android的每一個屏幕基本上就是一個Activity，屏幕間的切換實際上就是在互相調用的過程，Android使用Intent完成這個動作。包括兩種跳轉：無返回值和有返回值。

 

一、無返回值跳轉

    

public void onClick(View v) {
				Intent intent=new Intent(TestAndroidActivity.this,t2.class);
				startActivity(intent);
			}

 

二、帶有返回值的跳轉

 ReceiveResult.java片段

static final private GET_CODE = 0;

public void onClick(View v) {
            // Start the activity whose result we want to retrieve.  The
            // result will come back with request code GET_CODE.
            Intent intent = new Intent(ReceiveResult.this, SendResult.class);
            startActivityForResult(intent, GET_CODE);
        }

SendResult.java片段

public class SendResult extends Activity
{
    /**
     * Initialization of the Activity after it is first created.  Must at least
     * call {@link android.app.Activity#setContentView setContentView()} to
     * describe what is to be displayed in the screen.
     */
    @Override
	protected void onCreate(Bundle savedInstanceState)
    {
        // Be sure to call the super class.
        super.onCreate(savedInstanceState);

        // See assets/res/any/layout/hello_world.xml for this
        // view layout definition, which is being set here as
        // the content of our screen.
        setContentView(R.layout.send_result);

        // Watch for button clicks.
        Button button = (Button)findViewById(R.id.corky);
        button.setOnClickListener(mCorkyListener);
        button = (Button)findViewById(R.id.violet);
        button.setOnClickListener(mVioletListener);
    }

    private OnClickListener mCorkyListener = new OnClickListener()
    {
        public void onClick(View v)
        {
            // To send a result, simply call setResult() before your
            // activity is finished.
            setResult(RESULT_OK, (new Intent()).setAction("Corky!"));
            finish();
        }
    };

    private OnClickListener mVioletListener = new OnClickListener()
    {
        public void onClick(View v)
        {
            // To send a result, simply call setResult() before your
            // activity is finished.
            setResult(RESULT_OK, (new Intent()).setAction("Violet!"));
            finish();
        }
    };
}

ReceiveResult.java 片段

protected void onActivityResult(int requestCode, int resultCode,
		Intent data) {
        // You can use the requestCode to select between multiple child
        // activities you may have started.  Here there is only one thing
        // we launch.
        if (requestCode == GET_CODE) {

            // We will be adding to our text.
            Editable text = (Editable)mResults.getText();

            // This is a standard resultCode that is sent back if the
            // activity doesn't supply an explicit result.  It will also
            // be returned if the activity failed to launch.
            if (resultCode == RESULT_CANCELED) {
                text.append("(cancelled)");

            // Our protocol with the sending activity is that it will send
            // text in 'data' as its result.
            } else {
                text.append("(okay ");
                text.append(Integer.toString(resultCode));
                text.append(") ");
                if (data != null) {
                    text.append(data.getAction());
                }
            }

            text.append("\n");
        }