1、复制文本到剪切板

ClipboardManager clipboard = (ClipboardManager) getSystemService(Context.CLIPBOARD_SERVICE);
ClipData clipData = ClipData.newPlainText("key0", "你好吗？？");
clipboard.setPrimaryClip(clipData);

2、从剪切板中获取文本

public class MainActivity extends AppCompatActivity {

    private Handler handler = new Handler(Looper.myLooper()){
        @Override
        public void handleMessage(@NonNull Message msg) {
            super.handleMessage(msg);
            ClipboardManager clipboard = (ClipboardManager) getSystemService(Context.CLIPBOARD_SERVICE);
            // If the clipboard doesn't contain data, disable the paste menu item.
            // If it does contain data, decide if you can handle the data.
            if (!(clipboard.hasPrimaryClip())) {
                Toast.makeText(MainActivity.this, "剪切板无数据", Toast.LENGTH_SHORT).show();
            } else if (!(clipboard.getPrimaryClipDescription().hasMimeType(MIMETYPE_TEXT_PLAIN))) {
                // This disables the paste menu item, since the clipboard has data but it is not plain text
                Toast.makeText(MainActivity.this, "剪切板内不是纯文本数据", Toast.LENGTH_SHORT).show();
            } else {
                // This enables the paste menu item, since the clipboard contains plain text.
                ClipData.Item item = clipboard.getPrimaryClip().getItemAt(0);
                String pasteData = item.getText().toString();
                Toast.makeText(MainActivity.this, pasteData, Toast.LENGTH_SHORT).show();
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //Android 10 中 只有默认输入法(IME)或者是目前处于焦点的应用, 才能访问到剪贴板数据，所以此处加个延时
        handler.sendEmptyMessageDelayed(100,500);
    }
}

3、官方文档

https://developer.android.google.cn/guide/topics/text/copy-paste.html#java