Intent之学习二（Activity间数据的传递）

Activity的启动常常有两种方式：startActivity()与startActivityForResult()。接下来，就以这两种方式为例讲解使用Intent在Activity间进行数据的传递。

1、startActivity()

2、startActivityForResult()

1、startActivity()

用到的函数：startActivity(Intent intent)

从FirstActivity点击button1启动SecondActivity，在SecondActivity使用Log方式查看Intent传递的数据。

代码段

FirstActivity.class

Button button1 = (Button)findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(FirstActivity.this, SecondActivity.class);
int data = 1;
intent.putExtra("ExtraData",data);
startActivity(intent);
}
});

SecondActivity.class

Intent intent = getIntent();
int data = intent.getIntExtra("ExtraData",-1);
Log.d("SecondActivity",Integer.toString(data));

2、startActivityForResult()

用到的函数：

startActivityForResult(Intent intent, int requestCode)

setResult(int resultCode,Intent intent)

onActivityResult(int requestCode,int resultCode,Intent data)

从FirstActivity点击button1启动SecondActivity，并将Intent附带数据传给SecondActivity，在SecondActivity使用Log方式查看传递的数据。

从FirstActivity点击button3启动ThirdActivity,此处Intent没有附带数据。

分别从SecondActivity与ThirdActivity点击返回按键回到FirstActivity，并将Intent附带数据用Log方式打印出来。

代码段

FirstActivity.class

Button button1 = (Button)findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(FirstActivity.this, SecondActivity.class);
int data = 1;
intent.putExtra("ExtraData", data);
startActivityForResult(intent,2);
}
});

//隐式intent启动activity3
Button button3 = (Button)findViewById(R.id.button3);
button3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent("com.example.test.ACTION_START");
intent.addCategory("com.example.test.MY_CATEGORY");
startActivityForResult(intent, 3);
}
});

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode){
case 2:
if (resultCode==RESULT_OK){
String return_data = data.getStringExtra("return");
Log.d("FirstActivity",return_data);
}
case 3:
if (resultCode==RESULT_OK){
String return_data = data.getStringExtra("return");
Log.d("FirstActivity",return_data);
}
}
}

SecondActivity.class

Intent intent = getIntent();
int data = intent.getIntExtra("ExtraData",-1);
Log.d("SecondActivity", Integer.toString(data));

@Override
public void onBackPressed() {
Intent intent = new Intent();
intent.putExtra("return","Second_to_First");
setResult(RESULT_OK,intent);
finish();
}

ThirdActivity.class

@Override
public void onBackPressed() {
Intent intent = new Intent();
intent.putExtra("return", "Third_to_First");
setResult(RESULT_OK, intent);
finish();
}