andriod java实现备忘录代码

好的，以下是一个简单的备忘录的安卓Java代码，您可以参考一下：

MainActivity.java

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    private EditText mEditText;
    private Button mButton;
    private ListView mListView;

    private ArrayList<String> mMemoList;
    private MemoAdapter mAdapter;

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

        mEditText = findViewById(R.id.editText);
        mButton = findViewById(R.id.button);
        mListView = findViewById(R.id.listView);

        mMemoList = new ArrayList<>();
        mAdapter = new MemoAdapter(this, mMemoList);
        mListView.setAdapter(mAdapter);

        mButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String memo = mEditText.getText().toString();
                if (memo.isEmpty()) {
                    Toast.makeText(MainActivity.this, "请输入备忘录", Toast.LENGTH_SHORT).show();
                } else {
                    mMemoList.add(memo);
                    mAdapter.notifyDataSetChanged();
                    mEditText.setText("");
                }
            }
        });
    }
}

MemoAdapter.java

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

import java.util.ArrayList;

public class MemoAdapter extends ArrayAdapter<String> {

    private Context mContext;
    private ArrayList<String> mMemoList;

    public MemoAdapter(Context context, ArrayList<String> memoList) {
        super(context, 0, memoList);
        mContext = context;
        mMemoList = memoList;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View listItem = convertView;
        if (listItem == null) {
            listItem = LayoutInflater.from(mContext).inflate(R.layout.memo_item, parent, false);
        }

        String memo = mMemoList.get(position);

        TextView memoText = listItem.findViewById(R.id.memoText);
        memoText.setText(memo);

        return listItem;
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/editText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:hint="请输入备忘录"
        android:textSize="18sp" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/editText"
        android:layout_alignParentEnd="true"
        android:layout_marginEnd="16dp"
        android:layout_marginTop="16dp"
        android:text="添加" />

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@id/button"
        android:layout_marginTop="16dp" />

</RelativeLayout>

memo_item.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/memoText"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="16dp"
    android:textSize="18sp" />

这个备忘录应用程序简单地使用了一个 EditText 用于输入备忘录，一个 Button 用于添加备忘录，以及一个 ListView 用于显示备忘录列表。在添加备忘录时，它将备忘录添加到 ArrayList 中，并通知适配器更新 ListView。最后，您需要创建 MemoAdapter 类来将备忘录列表显示在 ListView 中。