Android两个Activity之间的数据交换

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
next=(Button)findViewById(R.id.next);
next.setOnClickListener(new Button.OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
 Intent intent=new Intent();
intent.setClass(MainActivity.this, Second.class);
startActivity(intent);
}
});
}

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
next=(Button)findViewById(R.id.next);
content=(EditText)findViewById(R.id.content);
next.setOnClickListener(new Button.OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
String name=content.getText().toString();
  Intent intent=new Intent();
intent.putExtra("name", name);
//Toast.makeText(MainActivity.this, name, Toast.LENGTH_SHORT).show();
intent.setClass(MainActivity.this, Second.class);
startActivity(intent); 
}
});
}

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
name=(TextView)findViewById(R.id.name);
age=(EditText)findViewById(R.id.age);
back=(Button)findViewById(R.id.back);

Intent intent=getIntent();
String na=intent.getStringExtra("name");
//Toast.makeText(Second.this, na, Toast.LENGTH_SHORT).show();
        name.setText(na);
    }

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
next=(Button)findViewById(R.id.next);
content=(EditText)findViewById(R.id.content);
next.setOnClickListener(new Button.OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
String name=content.getText().toString();
Intent intent=new Intent();
intent.putExtra("name", name);
//Toast.makeText(MainActivity.this, name, Toast.LENGTH_SHORT).show();
intent.setClass(MainActivity.this, Second.class);
                startActivityForResult(intent, RESULT_CODE);   
}
});
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// TODO Auto-generated method stub
super.onActivityResult(requestCode, resultCode, data);
if(requestCode==RESULT_CODE){
if(resultCode==Second.RESULT_CODE){
Bundle bundle=data.getExtras();
String con=bundle.getString("age");
content.setText(con);
            }
}

}

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
name=(TextView)findViewById(R.id.name);
age=(EditText)findViewById(R.id.age);
back=(Button)findViewById(R.id.back);
back.setOnClickListener(new Button.OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
String a=age.getText().toString();
 Intent intent=new Intent();
Bundle bundle=new Bundle();
bundle.putString("age", a);
intent.putExtras(bundle);
setResult(RESULT_CODE, intent);
finish();
            }
});

Intent intent=getIntent();
String na=intent.getStringExtra("name");
//Toast.makeText(Second.this, na, Toast.LENGTH_SHORT).show();
name.setText(na);
}