Question

我有两项活动

第一项活动 -

用于获取editText
将值传递给第二个活动

第二项活动 -

从第一项活动中获取价值
将值放在ArrayList中并在listview中显示
将值放入集合并存储在共享首选项中。

我希望这些事情发生，但我不知道我的代码存在问题。我的ListView不显示任何内容。

这是我的代码：

第一项活动

public class History extends AppCompatActivity {
Button translate;
Button next;
EditText enterText;

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

    enterText = findViewById(R.id.editText);
    next = findViewById(R.id.btnNext);

    translate = findViewById(R.id.buttonTranslate);
    View.OnClickListener addlistener = new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
            imm.hideSoftInputFromWindow(enterText.getWindowToken(), 0);

            if(enterText != null)
            {
                String input = enterText.getText().toString();
                Intent i= new Intent(History.this,MainActivity.class);
                i.putExtra("myHistory",input);
                enterText.setText("");

            }else
            {
                Toast.makeText(getBaseContext(),"Input Field is empty",Toast.LENGTH_SHORT).show();
            }
        }

    };
    translate.setOnClickListener(addlistener);
    next.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent intent = new Intent(History.this,MainActivity.class);
            startActivity(intent);
        }
    });

第二项活动

    public class MainActivity extends AppCompatActivity {
    private ListView listView;
    private ArrayAdapter<String> adapter;
    private ArrayList<String> toDelete;
    ArrayList<String> itemList = new ArrayList<String>();
    SharedPreferences.Editor editor ;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, itemList);
        toDelete = new ArrayList<>();

        listView = findViewById(R.id.listView);
        listView.setAdapter(adapter);

        final SharedPreferences transHistory  = getSharedPreferences("SaveHistory",Context.MODE_PRIVATE);
        final Set<String> tHistory = new HashSet<String>();
        Bundle extras = getIntent().getExtras();
        if (extras != null) {
            String value = extras.getString("myHistory");
            itemList.add(value);
            tHistory.addAll(itemList);
        }
        editor = transHistory.edit();
        editor.putStringSet("history",tHistory);
        editor.apply();

        adapter.notifyDataSetChanged();
}

Answer 1

你做了语法错误： -

                String input = enterText.getText().toString();
                Intent i= new Intent(History.this,MainActivity.class);
                i.putExtra("myHistory",input);
                enterText.setText("");

这样做： -

                String input = enterText.getText().toString();
                Intent i= new Intent(History.this,MainActivity.class);
                i.putExtra("myHistory",input);
                enterText.setText("");
                startActivity(i);

并在第二个活动中执行此操作： -

public class MainActivity extends AppCompatActivity {
private ListView listView;
private ArrayAdapter<String> adapter;
private ArrayList<String> toDelete;
ArrayList<String> itemList = new ArrayList<String>();
SharedPreferences.Editor editor ;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

Bundle extras = getIntent().getExtras();
    if (extras != null) {
        String value = extras.getString("myHistory");
        itemList.add(value);
        tHistory.addAll(itemList);
    }

    adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, itemList);
    toDelete = new ArrayList<>();

    listView = findViewById(R.id.listView);
    listView.setAdapter(adapter);

    final SharedPreferences transHistory  = getSharedPreferences("SaveHistory",Context.MODE_PRIVATE);
    final Set<String> tHistory = new HashSet<String>();

    editor = transHistory.edit();
    editor.putStringSet("history",tHistory);
    editor.apply();

    adapter.notifyDataSetChanged();

ListView不显示来自另一个活动的值传递

1 个答案: