利用Intent启动activity的例子

 1 不带回调的调起和返回

调起

        //获取Intent
        Intent intent = new Intent(this,Main2Activity.class);
        //获取输入框中的数据
        String par = et_par.getText().toString();
        //把参数放到inten里面传递
        intent.putExtra("par",par);
        //启动Activity
        int requestCode =2;
        startActivityForResult(intent,requestCode);

返回

this.finish();

2 带结果的调起和返回

调起  

//获取Intent
Intent intent = new Intent(this,Main2Activity.class);
//获取输入框中的数据
String par = et_par.getText().toString();
//把参数放到inten里面传递
intent.putExtra("par",par);
//启动Activity
int requestCode =2;
startActivityForResult(intent,requestCode);

@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
    //super.onActivityResult(requestCode, resultCode, data);
    if(requestCode==2&&resultCode==3){
        String par = data.getStringExtra("par");
        et_par.setText(par);
    }
}

返回

int resultCode = 3;
Intent data = new Intent();
String val = et_par2.getText().toString();
data.putExtra("par",val);
setResult(resultCode,data);
this.finish();