Activity初级：resultCode返回码、 onclick代码重构

主页：

public class MainActivity extends Activity
{
    /**
     * 主页点击按钮跳转到第二页
     * 第二页点击按钮1将字符串内容显示到主页，点击按钮2将数字内容显示到主页
     */
    private final static int RESULT_CODE_ONE = 1;
    private final static int RESULT_CODE_TWO = 2;
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        super.onActivityResult(requestCode, resultCode, data);
        TextView textView = (TextView) findViewById(R.id.textView1_main);
        String text = null;
        switch (resultCode)//判断返回码
        {
            case RESULT_CODE_ONE:
                text = "from按钮1:" + data.getStringExtra("btnone");
                break;
            case RESULT_CODE_TWO:
                int age = data.getIntExtra("btntwo", 0);//0为默认值，当data没有接收到返回的int时，返回这个默认值
                text ="from按钮2:"+ String.valueOf(age);
                break;
            default:
                break;
        }
        textView.setText(text);
    }
                                                          
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
                                                              
        findViewById(R.id.button1_main).setOnClickListener(new OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                Intent intent = new Intent(MainActivity.this, SecondActivity.class);
                startActivityForResult(intent , 0);
            }
        });
    }
                                                          
    @Override
    public boolean onCreateOptionsMenu(Menu menu)
    {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
}

第二页

public class SecondActivity extends Activity
{
    private final static int RESULT_CODE_ONE = 1;
    private final static int RESULT_CODE_TWO = 2;
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        final Intent data = new Intent();
        findViewById(R.id.button1).setOnClickListener(new OnClickListener()
        {
                                             
            @Override
            public void onClick(View v)
            {
                data.putExtra("btnone", "name");
                setResult(RESULT_CODE_ONE, data );//设置返回码
                finish();
            }
        });
                                         
        findViewById(R.id.button2).setOnClickListener(new OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                data.putExtra("btntwo", 12);
                setResult(RESULT_CODE_TWO, data );//设置返回码
                finish();
            }
        });
                                         
    }
                                     
    @Override
    public boolean onCreateOptionsMenu(Menu menu)
    {
        getMenuInflater().inflate(R.menu.second, menu);
        return true;
    }
}

第二页按钮事件重构过程一：

1.实现OnClickListener接口

2.重写onClick(View v)

3.findViewById(R.id.button1).setOnClickListener(this)

public class SecondActivity extends Activity implements OnClickListener//实现监听者接口
{
    private final static int RESULT_CODE_ONE = 1;
    private final static int RESULT_CODE_TWO = 2;
             
    @Override
    public void onClick(View v)//重写点击方法
    {
        Intent data = new Intent();
        if(v.getId() == R.id.button1)//判断view的id
        {
            data.putExtra("btnone", "name");
            setResult(RESULT_CODE_ONE, data );
            finish();
        }
        if(v.getId() == R.id.button2)
        {
            data.putExtra("btntwo", 12);
            setResult(RESULT_CODE_TWO, data );
            finish();
        }
    }
              
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
                  
        findViewById(R.id.button1).setOnClickListener(this);//监听按钮
        findViewById(R.id.button2).setOnClickListener(this);
    }
              
    @Override
    public boolean onCreateOptionsMenu(Menu menu)
    {
        getMenuInflater().inflate(R.menu.second, menu);
        return true;
    }
}

第二页按钮事件重构过程二：将事件内容以方法代替

public class SecondActivity extends Activity implements OnClickListener//实现监听者接口
{
    private final static int RESULT_CODE_ONE = 1;
    private final static int RESULT_CODE_TWO = 2;
          
    @Override
    public void onClick(View v)//重写点击方法
    {
        Intent data = new Intent();
        if(v.getId() == R.id.button1)//判断view的id
        {
//            data.putExtra("btnone", "name");
//            setResult(RESULT_CODE_ONE, data );
//            finish(); 
            sendResult("btnone", "name", RESULT_CODE_ONE);
        }
        if(v.getId() == R.id.button2)
        {
//            data.putExtra("btntwo", 12);
//            setResult(RESULT_CODE_TWO, data );
//            finish();
            sendResult("btntwo", Integer.valueOf(12), RESULT_CODE_TWO);
        }
    }
           
           
    private void sendResult(String extraKey, Object content, int resultCode)
    {
        Intent data = new Intent();
        if (content instanceof String)
        {
            data.putExtra(extraKey, (String) content);
        }
        else if (content instanceof Integer)
        {
            data.putExtra(extraKey, (Integer) content);
        }
        setResult(resultCode, data);
        finish();
    }
           
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
               
        findViewById(R.id.button1).setOnClickListener(this);//监听按钮
        findViewById(R.id.button2).setOnClickListener(this);
    }
           
    @Override
    public boolean onCreateOptionsMenu(Menu menu)
    {
        getMenuInflater().inflate(R.menu.second, menu);
        return true;
    }
}

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