Android开发中的Intent和Activity

周末撸了几次代码，

舍不得扔，

立此为照！

mainActivity.java

package com.tw.flag.ch08_memo;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class MainActivity extends AppCompatActivity
    implements AdapterView.OnItemClickListener, AdapterView.OnItemLongClickListener {
    String[] aMemo = {
            "1.单击可以编辑备忘",
            "2.长按可以清除备忘", "3.", "4.", "5.", "6" };
    ListView lv;
    ArrayAdapter<String> aa;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        lv = (ListView)findViewById(R.id.listView);
        aa = new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, aMemo);
        lv.setAdapter(aa);

        lv.setOnItemClickListener(this);
        lv.setOnItemLongClickListener(this);
    }

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        Intent it = new Intent(this, Edit.class);
        it.putExtra("备忘", aMemo[position]);
        startActivityForResult(it, position);

    }

    protected void onActivityResult(int requestCode, int resultCode, Intent it) {
        if (resultCode == RESULT_OK) {
            aMemo[requestCode] = it.getStringExtra("备忘");
            aa.notifyDataSetChanged();
        }
    }

    @Override
    public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
        aMemo[position] = (position+1) + ".";
        aa.notifyDataSetChanged();
        return true;
    }
}

package com.tw.flag.ch08_memo;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

public class Edit extends AppCompatActivity {
    TextView txv;
    EditText edt;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_edit);

        Intent it = getIntent();
        String s = it.getStringExtra("备忘");

        txv = (TextView)findViewById(R.id.textView);
        txv.setText(s.substring(0, 2));

        edt = (EditText)findViewById(R.id.editText);
        if (s.length() > 3)
            edt.setText(s.substring(3));
    }

    public void onCancel(View v) {
        setResult(RESULT_CANCELED);
        finish();
    }

    public void onSave(View v) {
        Intent it2 = new Intent();
        it2.putExtra("备忘", txv.getText() + " " + edt.getText());
        setResult(RESULT_OK, it2);
        finish();
    }
}