Android返回数据给上一个活动

第一个界面

web.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this,SecondActivity.class);
                //第二个参数是请求码
                startActivityForResult(intent,1);
            }
        });

//requestCode是判断数据来源,resultCode是判断处理结果是否成功
@Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        switch (requestCode) {
            case 1:
                if (resultCode == RESULT_OK){
                    String data1 = data.getStringExtra("data");
                    Toast.makeText(this, ""+data1, Toast.LENGTH_SHORT).show();
                    Log.e("MainActivity---", "onActivityResult: "+data1 );
                }
        }
    }

第二个界面

back.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.putExtra("data","Hello");
                setResult(RESULT_OK,intent);
                finish();
            }
        });